Evaluation of serum fructosamine concentration as an index of blood glucose control in cats with diabetes mellitus.

Fructosamine, a glycated serum protein, was evaluated as an index of glycemic control in normal and diabetic cats. Fructosamine was determined manually by use of a modification of an automated method. The within-run precision was 2.4 to 3.2%, and the day-to-day precision was 2.7 to 3.1%. Fructosamine was found to be stable in serum samples stored for 1 week at 4 C and for 2 weeks at -20 C. The reference range for serum fructosamine concentration in 31 clinically normal colony cats was 2.19 to 3.47 mmol/L (mean, 2.83 +/- 0.32 mmol/L). In 27 samples from 16 cats with poorly controlled diabetes mellitus, the range for fructosamine concentration was 3.04 to 8.83 mmol/L (mean, 5.93 +/- 1.35 mmol/L). Fructosamine concentration was directly and highly correlated to blood glucose concentration. Fructosamine concentration also remained high in consort with increased blood glucose concentration in cats with poorly controlled diabetes mellitus over extended periods. It is concluded that measurement of serum fructosamine concentration can be a valuable adjunct to blood glucose monitoring to evaluate glycemic control in diabetic cats. The question of whether fructosamine can replace glucose for monitoring control of diabetes mellitus requires further study.     

Serum fructosamine concentrations in hyperthyroid cats.

Serum fructosamine concentrations were measured in 35 healthy cats and in 30 hyperthyroid cats before and 30 days after curative radioiodine ((131)I) treatment. Hyperthyroid cats were divided into those with 30 day post-treatment total thyroxine (T4) concentrations within (EuT4) or below (HypoT4) the reference range. The median (semi-interquartile range, SIR) fructosamine concentration was significantly lower in hyperthyroid compared with healthy cats (295. 0 (18.5) micromol l(-1)) both before (254.0 (27.6) micromol l(-1)) and after (268.5 (28.0) micromol l(-1)) treatment (P < 0.001 in each case). (131)I therapy was associated with increases in serum fructosamine (mean increase 20.4 micromol l(-1), P = 0.039) and total protein (6.3 g l(-1), P < 0.002) in the HypoT4 group and in globulin concentration in both EuT4 (5.9 g l(-), P < 0.002) and HypoT4 (5.2 g l(-1), P = 0.023) groups. There were no direct relationships between the observed elevations in fructosamine concentration and those in total protein or globulin concentrations suggesting that the effect may be due to reduced rates of protein turnover. Reduced values may need to be considered when interpreting serum fructosamine concentrations for monitoring the degree of glycaemic control in diabetic cats with concurrent hyperthyroidism.     

Serum fructosamine concentration in nondiabetic and diabetic cats

Differentiating transient hyperglycemia from diabetic hyperglycemia can be difficult in cats since single blood glucose measurements reflect only momentary glucose concentrations, and values may be elevated because of stress-induced hyperglycemia. Glycated protein measurements serve as monitors of longer-term glycemic control in human diabetics. Using an automated nitroblue tetrazolium assay, fructosamine concentration was measured in serum from 24 healthy control cats and 3 groups of hospitalized cats: 32 euglycemic, 19 transiently hyperglycemic, and 12 diabetic cats. Fructosamine concentrations ranged from 2.1 - 3.8 mmol/L in clinically healthy cats; 1.1 - 3.5 mmol/L in euglycemic cats; 2.0 - 4.1 mmol/L in transiently hyperglycemic cats; and 3.4 to >6.0 mmol/L in diabetic cats. Values for with-in-run precision at 2 fructosamine concentrations (2.64 mmol/L and 6.13 mmol/L) were 1.5% and 1.3%, respectively. Between-run coefficient of variation was 3.8% at a fructosamine concentration of 1.85 mmol/L. The mean fructosamine concentration for the diabetic group differed significantly (P=0.0001) from the mean concentrations of the other 3 groups. Poorly regulated or newly diagnosed diabetic cats tended to have the highest fructosamine values, whereas well-regulated or over-regulated diabetic cats had values approaching the reference range. As a single test for differentiating nondiabetic cats from diabetic cats, fructosamine was very sensitive (92%) and specific (96%), with a positive predictive value of 85% and a negative predictive value of 98%. Serum fructosamine concentration shows promise as an inexpensive, adjunct diagnostic tool for differentiating transiently hyperglycemic cats from poorly controlled diabetic cats.     

Relation of fructosamine to serum protein, albumin, and glucose concentrations in healthy and diabetic dogs.

The relation of the glycated serum protein, fructosamine, to serum protein, albumin, and glucose concentrations was examined in healthy dogs, dogs with hypo- or hyperproteinemia, and diabetic dogs. Fructosamine was determined by use of an adaptation of an automated kit method. The reference range for fructosamine in a composite group of control dogs was found to be 1.7 to 3.38 mmol/L (mean +/- SD, 2.54 +/- 0.42 mmol/L). Fructosamine was not correlated to serum total protein, but was highly correlated to albumin in dogs with hypoalbuminemia. To normalize the data with respect to albumin, it is suggested that the lower limit of the reference range for albumin concentration (2.5 g/dl) be used for adjustment of fructosamine concentration and only in hypoalbuminemic dogs. In 6 hyperglycemic diabetic dogs, fructosamine concentration was well above the reference range. It is concluded that although fructosamine may be a potentially useful guide to assess the average blood glucose concentration over the preceding few days in dogs, further study is required to establish its value as a guide to glucose control in diabetic dogs.     

Fructosamine concentrations in hyperglycemic cats.

The aims of this study were 1) to establish a reference range for fructosamine in cats using a commercial fructosamine kit; 2) to demonstrate that the fructosamine concentration is not increased by transient hyperglycemia of 90 min duration, simulating hyperglycemia of acute stress; and 3) to determine what percentage of blood samples submitted to a commercial laboratory from 95 sick cats had evidence of persistent hyperglycemia based on an elevated fructosamine concentration. Reference intervals for the serum fructosamine concentration were established in healthy, normoglycemic cats using a second generation kit designed for the measurement of the fructosamine concentration in humans. Transient hyperglycemia of 90 min duration was induced by IV glucose injection in healthy cats. Multisourced blood samples that were submitted to a commercial veterinary laboratory either as fluoride oxalated plasma or serum were used to determine the percentage of hyperglycemic cats having persistent hyperglycemia. The reference interval for the serum fructosamine concentration was 249 to 406 mumol/L. Transient hyperglycemia of 90 min duration did not increase the fructosamine concentration and there was no correlation between fructosamine and blood glucose. In contrast, the fructosamine concentration was correlated with the glucose concentration in sick hyper- and normoglycemic cats. It is concluded that the fructosamine concentration is a useful marker for the detection of persistent hyperglycemia and its differentiation from transient stress hyperglycemia. Fructosamine determinations should be considered when blood glucose is 12 to 20 mmol/L and only a single blood sample is available for analysis.     

Serum fructosamine measurement: a new diagnostic approach to renal glucosuria in dogs

Measurement of serum fructosamine, 1-amino-1-deoxyfructose, is commonly used in diagnosing and monitoring hyperglycaemic disorders, such as diabetes mellitus in dogs. Serum fructosamine indicates long-term serum glucose concentrations and replaces serial serum glucose measurements. This study investigates the clinical usefulness of serum fructosamine in differentiating conditions other than diabetes mellitus characterised by glucosuria. Four dogs presented with glucosuria all had serum fructosamine concentrations within or close to the reference range (313 micromol 1(-1), 291 micromol 1(-1), 348 micromol 1(-1), 262 micromol 1(-1) reference range: 250 to 320 micromol 1(-1) indicating that a single serum fructosamine measurement is a simple and efficient way of verifying concurrent persistent normoglycaemia. Therefore, serum fructosamine is a useful parameter not only in diabetic patients, bu also in differentiating conditions in dogs characterised by glucosuria without hyperglycaemia, such as primary renal glucosuria and the Fanconi syndrome. To distinguish between primary renal glucosuria and the Fanconi syndrome, measurement of the amino acid concentration in urine was performed.     

Clinical usefulness of fructosamine measurements in diagnosing and monitoring feline diabetes mellitus

Fructosamines are glycated serum proteins that reflect long-term serum glucose concentrations in humans and several animal species. In the present study, blood samples were drawn from three populations of diabetic cats: untreated diabetic cats with clinical symptoms prevailing only a few days (n = 1), untreated diabetic cats with symptoms lasting more than two weeks (n = 6) and clinically well stabilised diabetic cats receiving insulin twice daily which showed no signs of disease (n = 4). All untreated diabetic cats showed elevated fructosamine measurements. Based on fructosamine measurements, clinically well stabilised diabetic cats could be subdivided further according to the degree of glycaemic control. Diabetic cats with satisfactory glycaemic control revealed fructosamine concentrations within or close to the reference range (146 to 271 umol/litre), whereas fructosamine concentrations above 400 umol/litre indicated insufficient glycaemic control. This study suggests that the fructosamine assay reflects persistently elevated serum glucose concentrations in cats and is a useful parameter for diagnosing and monitoring diabetes mellitus in cats.     

Serum Fructosamine Concentration as an Index of Glycemia in Cats With Diabetes Mellitus and Stress Hyperglycemia

The purpose of this study was to evaluate fructosamine concentrations in clinically healthy cats, sick cats with stress hyperglycemia, and untreated diabetic cats to determine the usefulness of this test in diagnosing diabetes mellitus in cats, and in differentiating the disease from stress-induced hyperglycemia. In addition, we evaluated if the degree of glycemic control in cats treated for diabetes influenced their serum fructosamine concentrations. In the 14 sick cats with stress hyperglycemia, the median serum fructosamine concentration (269 μmol/L) was not significantly different from the median value in the 26 clinically normal cats (252 μmol/L). Two of the 14 cats with stress hyperglycemia (14.3%) had serum fructosamine concentrations above the upper limit of the reference range (175 to 400 μmol/U; on the basis of these results, the test specificity was calculated as 0.86. In 30 cats with untreated diabetes mellitus, the median serum fructosamine concentration was 624 μmol/L, markedly higher than the value in either the normal cats or the cats with stress hyperglycemia. All but 2 of the 30 untreated diabetic cats (6.7%) had serum fructosamine concentration above the upper limit of the reference range; on the basis of these results, the sensitivity of serum fructosamine concentration as a diagnostic test for diabetes mellitus was 0.93. When 30 diabetic cats receiving treatment were divided into 3 groups according to their response to treatment (ie, poor, fair, and good), the 16 cats that had a good response to treatment had significantly lower serum concentrations of both glucose and fructosamine compared with cats that had either a fair or poor response to treatment. A significant correlation (r_s= .70, n = 100, P < .001) was found between serum concentrations of glucose and fructosamine. Results of this study indicate that quantification of serum fructosamine concentration is a meaningful test for the diagnosis of diabetes, for differentiating diabetes from stress hyperglycemia; and for monitoring the metabolic control in treated diabetic cats.     

Determination of a reference range for fructosamine in feline serum samples

Fructosamine, the product of a non-enzymatic reaction between glucose and serum proteins, is a component of serum which reflects long-term deviations from normal glucose and protein homeostasis. Thirty-one healthy, intact, domestic short-haired cats, living under uniform feeding and environmental conditions, were sampled to calculate a reference range for feline serum fructosamine. The results were obtained using a nitroblue tetrazolium colorimetric method. The analytical assay was evaluated by calculation of within-run and between-day variation, detection limit, and accuracy. Serum fructosamine concentrations were approximately normally distributed and the calculated reference range was 146–271 µmol/L (mean 209 µmol/L, standard deviation 31.6 µmol/L). There were no significant differences between male and female cats, or between cats older and younger than 12 months. Previously conducted studies give higher reference ranges, possibly because of differences in the test procedure and homogeneity of the test population.Abbreviations CL confidence limits - NBT nitroblue tetrazolium     

Serum fructosamine concentrations in 59 dogs naturally Infected with Angiostrongylus vasorum

Retrospectively, 89 cases of dogs infected with Angiostrongylus vasorum were examined. Fifty-nine of these 89 dogs fulfilled the criteria of not being dually infected with Crenosoma vulpis as well as having a full biochemistry profile including serum fructosamine available. The mean serum fructosamine value of the 59 dogs was 236 micromol/l (reference value 258-348 micromol/l) and significantly lower than the serum fructosamine level of 314 micromol/l in a control group of 42 clinically healthy dogs. Eleven dogs were available for follow up after successful treatment of angiostrongylosis. In this group, the serum fructosamine value rose from a mean of 244 micromol/l to a mean of 320 micromol/l following treatment. Serum glucose, albumin and protein were all within the respective reference ranges at all sampling points. The results indicate that serum fructosamine could be affected by infection with A. vasorum. Furthermore, this change cannot be explained by measurable changes in the level of glucose, albumin or protein. The clinical impact of this study is that a low fructosamine value may indicate infection with A. vasorum thereby suggesting a Baermann test to be performed.     

Serum fructosamine concentration in cats with overt hyperthyroidism.

OBJECTIVE: To determine the effect of hyperthyroidism on serum fructosamine concentration in cats. DESIGN: Cohort study. ANIMALS: 22 cats with overt hyperthyroidism. PROCEDURE: Hyperthyroidism was diagnosed on the basis of clinical signs, detection of a palpable thyroid gland, and high total serum thyroxine (T4) concentrations. Hyperthyroid cats with abnormal serum albumin, total protein, and glucose concentrations were excluded from the study. Samples for determination of serum fructosamine concentration were obtained prior to initiating treatment. Results were compared with fructosamine concentrations in healthy cats, cats in which diabetes had recently been diagnosed, and cats with hypoproteinemia. In 6 cats, follow-up measurements were obtained 2 and 6 weeks after initiating treatment with carbimazole. RESULTS: Serum fructosamine concentrations ranged from 154 to 267 mumol/L (median, 198 mumol/L) and were significantly lower than values in healthy cats. Eleven (50%) of the hyperthyroid cats had serum fructosamine concentrations less than the reference range. Serum fructosamine concentrations in hyperthyroid, normoproteinemic cats did not differ from values in hypoproteinemic cats. During treatment, an increase in serum fructosamine concentration was detected. CONCLUSIONS AND CLINICAL RELEVANCE: In hyperthyroid cats, concentration of serum fructosamine may be low because of accelerated protein turnover, independent of blood glucose concentration. Serum fructosamine concentrations should not be evaluated in cats with overt hyperthyroidism and diabetes mellitus. Additionally, concentration of serum fructosamine in hyperthyroid cats should not be used to differentiate between diabetes mellitus and transitory stress-related hyperglycemia.     

Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus

This study compared the effects of a moderate carbohydrate-high fiber (MC-HF) food and a low carbohydrate-low fiber (LC-LF) food on glycemic control in cats with diabetes mellitus. Sixty-three diabetic cats (48 male castrated, 15 female spayed) were randomly assigned to be fed either a canned MC-HF (n = 32) food or a canned LC-LF (n = 31) food for 16 weeks. Owners were blinded to the type of diet fed. CBC, urinalysis, serum chemistry panel, fructosamine concentration and thyroxine concentration were determined on initial examination, and a complete blood count, serum chemistry panel, urinalysis and serum fructosamine concentration were repeated every 4 weeks for 16 weeks. Insulin doses were adjusted as needed to resolve clinical signs and lower serum fructosamine concentrations. Serum glucose (P = 0.0001) and fructosamine (P = 0.0001) concentrations significantly decreased from week 0 to week 16 in both dietary groups. By week 16, significantly more of the cats fed the LC-LF food (68%, 22/31), compared to the cats fed the MC-HF food (41%, 13/32), had reverted to a non-insulin-dependent state (P = 0.03). Cats in both groups were successfully taken off of insulin regardless of age, sex, type of insulin administered or duration of clinical disease before entering the study. There was no significant difference in the initial or final mean body weights or in the mean change in body weight from week 0 to week 16 between dietary groups. Diabetic cats in this study were significantly more likely to revert to a non-insulin-dependent state when fed the canned LC-LF food versus the MC-HF food.     

CLINICAL VALUE OF FRUCTOSAMINE MEASUREMENTS AND FRUCTOSAMINE-ALBUMIN RATIO IN HYPOGLYCEMIC FERRETS (MUSTELA PUTORIUS FURO)

The objective of this preliminary study was to establish a reference range for plasma fructosamine concentration and fructosamine-albumin ratio in healthy ferrets and to compare these reference intervals to values obtained from hypoglycemic ferrets. Fructosamine concentration has been shown to reflect blood glucose concentration over the previous 1 to 2 weeks in other animal species, and may be a useful indicator of chronic hypoglycemia in ferrets diagnosed with insulinoma. Plasma fructosamine was measured with an automated colorimetric assay using nitroblue tetrazolium. Thirty-two clinically healthy and 5 hypoglycemic ferrets were included in the study. The reference interval in healthy ferrets for fructosamine was 110 (98 to 123) – 203 (191 to 218) μmol/L, and the reference interval for plasma fructosamine-albumin ratio was 5.1 (4.6 to 5.6) – 8.6 (8.2 to 9.0) μmol/g. Results for hypoglycemic ferrets were within the ranges for both fructosamine and fructosamine-albumin ratio. As there were no significant differences between the healthy and hypoglycemic ferrets, this study suggests that fructosamine concentration and fructosamine-albumin ratio are not likely to be useful in determining insulinoma-associated chronic hypoglycemia in ferrets.     

Postprandial glycaemia in cats fed a moderate carbohydrate meal persists for a median of 12 hours -- female cats have higher peak glucose concentrations

The postprandial increase in glucose concentration is typically not considered in selecting diets to manage diabetic and pre-diabetic cats. This study describes increases in glucose and insulin concentrations in 24 clinically healthy, neutered adult cats following one meal (59 kcal/kg) of a moderate carbohydrate diet (25% of energy). Median time to return to baseline after feeding for glucose was 12.2 h (1.8-≥24 h) and for insulin was 12.3 h (1.5-≥24 h). Time to return to baseline for glucose was not different between male (10.2 h) and female (17.2 h) cats. There was evidence female cats had a longer return to baseline for insulin (18.9 h versus 9.8 h) and females had higher (0.9 mmol/l difference) peak glucose than males. This demonstrates that the duration of postprandial glycaemia in cats is markedly longer than in dogs and humans, and should be considered when managing diabetic and pre-diabetic cats.     

Evaluation of diabetes determinants in woolly monkeys (Lagothrix lagotricha)

Woolly monkeys (Lagothrix lagotricha) are a threatened specie in the wild with limited successful management in captivity due to diagnosed hypertension and suspected diabetic conditions. Six woolly monkeys with known hypertension problems were tested to determine if diabetes mellitus and current daily diet are underlying links to health problems for the captive population of this species. Blood and urine were collected and serum was analysed for fructosamine, glucose, glycated haemoglobin, insulin, triacylglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-Chol) and low-density lipoprotein cholesterol (LDL-Chol) while urine was tested for glucose concentrations. Diet disappearance was determined for 3 days prior to blood collection and nutrient content was calculated using Zoo Diet Analysis computer program. Serum analyses were within normal ranges (fructosamine (139-242 micromol/l), glucose (2.22-4.78 mmol/l), glycated haemoglobin (3.52-4.73%), insulin (6.2-13.0 microU/ml), triacylglycerides (0.38-3.4 mmol/l), total cholesterol (2.5-5.1 mmol/l), HDL-Chol (0.4-1.6 mmol/l) and LDL-Chol (1.8-3.4 mmol/l)). Urine glucose concentrations were below the detection limit. Diets were not limiting in starch and total sugars and were similar in non-starch polysaccharides. Potential dietary deficiencies were noted for vitamin A, vitamin D, calcium, phosphorus and selenium. When compared with the available primate reference ranges, the results do not indicate problems with diabetes mellitus or with glucose metabolism and therefore they are not causes of the diagnosed hypertension. Further research to ascertain the true cause of health related problems and the role of dietary factors is needed.     

Clinical efficacy and safety of a once-daily formulation of carbimazole in cats with hyperthyroidism

O bjective : Evaluation of efficacy and safety of a novel controlled-release formulation of carbimazole in feline hyperthyroidism.
M ethods : A multicentre, self-controlled study in 44 client-owned cats with history and clinical signs of hyperthyroidism, and total thyroxine concentration greater than or equal to 50 nmol/l. Treatment was started at 15 mg once daily, response assessed after 10 days, and 3, 5, 8, 26 and 53 weeks and dose adjusted as required.
R esults : The median dose of carbimazole was 10 mg (range 10 to 15 mg) and 15 mg (5 to 25 mg) once daily after 3 and 53 weeks, respectively. Median total thyroxine concentration dropped significantly from 118 nmol/l (50 to 320 nmol/l) at presentation to 33 nmol/l (n=40) after 10 days, 31 nmol/l (n=34) at 3 weeks and 21 nmol/l (n=18) at 53 weeks. Clinical signs improved or resolved in almost all cats within three weeks after starting treatment. Twenty-one adverse reactions possibly (20) or probably (1) related to treatment were reported. During treatment, increased blood urea nitrogen concentration was observed in 25 per cent of the cats, eosinophilia in 20 per cent and lymphopenia in 16 per cent, while liver enzymes tended to improve.
C linical S ignificance : Once daily administration of controlled-release carbimazole tablets was effective and had expected tolerance in hyperthyroid cats during short- and long-term treatment.     

Over representation of Burmese cats with diabetes mellitus

Objective To determine if Burmese cats in Queensland have an increased risk of diabetes mellitus.
Design A retrospective study of diabetic and nondiabetic cats that had blood submitted to a veterinary clinical laboratory over a 22 month study period.
Sample population 4402 cats
Procedure Cats were considered diabetic if blood glucose concentration was > 11 mmol/L and fructosamine was > 406 μmol/L or hydroxybutyrate was >1 mmol/L. Cats were grouped into Burmese and non-Burmese. Adjusted odds ratios of diabetes were calculated for breed, gender and age group amongst cats with blood glucose > 11 mmol/L.
Results Burmese cats comprised 20% of 45 diabetic cats of known breed, which was higher (P < 0.001) than among the normoglycemic reference population of 2203 cats (7% Burmese). There were more females among the diabetic Burmese (62%), but this did not differ (P > 0.05) from the Burmese reference population (45% females). In contrast, males seemed to predominate among diabetic non-Burmese (63%), although this also did not differ (P > 0.05) from the reference population (55%) or from diabetic Burmese (38% males). The majority (90%) of diabetic cats were older than 6 years, irrespective of breed (median age 12 years, interquartile range 10 to 13 years). This was higher (χ²= 8.13, P < 0.005) than among the normoglycaemic reference population, where 69% were older than 6 years.
Conclusions Burmese cats were significantly over represented among cats with diabetes mellitus. Irrespective of breed, the risk of diabetes in the study population increased with age.     

Diabetes mellitus in a koala (Phascolarctos cinereus)

Objective To describe a case of diabetes mellitus in a koala (Phascolarctos cinereus).
Design A case report with controls.
Procedures We describe clinical and laboratory findings in a 6-year-old, free-living, female koala presented with traumatic injury and subsequently found to have polydipsia, hyperglycaemia and glucosuria. Over a 5 week period, serum biochemical analyses, haematological examinations, urinal-yses, measurement of serum insulin and fructosamine concentrations, necropsy, histopathological examination of a range of tissues and immunohistochemical examination of the pancreas for insulin-containing cells were done. For reference purposes, serum insulin and fructosamine concentrations were determined in four and two healthy koalas, respectively, and three healthy koalas pancreases were examined histo-logically and immunohistochemically.
Results The koala had persistent hyperglycaemia, hyperlipidaemia, hyponatraemia, hypochloraemia and glucosuria. Serum insulin concentration of the diabetic koala was only marginally smaller than that of healthy koalas, but all concentrations were smaller than reference concentrations in dogs and people. Fructosamine concentration did not allow the diabetic koala to be distinguished from healthy koalas and concentrations of all koala analytes were greater than expected for healthy dogs and people. Histopathological examination revealed extensive degeneration of pancreatic islet cells and fatty infiltration of hepatocytes. Immunoperoxidase staining revealed decreased or absent insulin in the b cells of the affected koala.
Conclusion Clinical signs, clinicopathological results and histopathological changes were consistent with diabetes mellitus. The pathogenesis of the condition could not be determined but may have been related to the administration of a parenteral corticosteroid preparation, the stress of capture or tissue damage and inflammation.     

Diagnosis of hyperthyroidism in cats with mild chronic kidney disease

OBJECTIVES: In cats with concurrent hyperthyroidism and non-thyroidal illnesses such as chronic kidney disease, total thyroxine concentrations are often within the laboratory reference range (19 to 55 nmol/l). The objective of the study was to determine total thyroxine, free thyroxine and/or thyroid-stimulating hormone concentrations in cats with mild chronic kidney disease. METHODS: Total thyroxine, free thyroxine and thyroid-stimulating hormone were measured in three groups. The hyperthyroidism-chronic kidney disease group (n=16) had chronic kidney disease and clinical signs compatible with hyperthyroidism but a plasma total thyroxine concentration within the reference range. These cats were subsequently confirmed to be hyperthyroid at a later date. The chronic kidney disease-only group (n=20) had chronic kidney disease but no signs of hyperthyroidism. The normal group (n=20) comprised clinically healthy senior (>8 years) cats. RESULTS: In 4 of 20 euthyroid chronic kidney disease cats, free thyroxine concentrations were borderline or high (> or =40 pmol/l). In the hyperthyroidism-chronic kidney disease group, free thyroxine was high in 15 of 16 cats, while thyroid-stimulating hormone was low in 16 of 16 cats. Most hyperthyroidism-chronic kidney disease cats (14 of 16) had total thyroxine greater than 30 nmol/l, whereas all the chronic kidney disease-only cats had total thyroxine less than 30 nmol/l. CLINICAL SIGNIFICANCE: The combined measurement of free thyroxine with total thyroxine or thyroid-stimulating hormone may be of merit in the diagnosis of hyperthyroidism in cats with chronic kidney disease.     

Evaluation of fructosamine in dogs and cats with hypo- or hyperproteinaemia, azotaemia, hyperlipidaemia and hyperbilirubinaemia

The influence of various pathological conditions on fructosamine levels in normoglycaemic dogs and cats was investigated. The most frequent and most pronounced deviations were found in animals with hypoproteinaemia, in which fructosamine was significantly lower than in the controls. In 66 per cent of the dogs and 67 per cent of the cats with hypoproteinaemia the levels were below the reference range. In the dogs the concentration of fructosamine was correlated with the level of albumin, but in the cats it was correlated with the level of total protein. Dogs with hyperlipidaemia and azotaemia also had significantly lower levels of fructosamine; 38 per cent of those with hyperlipidaemia and 47 per cent of those with azotaemia had fructosamine levels outside the reference range. No significant changes in fructosamine were detected in dogs or cats with hyperproteinaemia or hyperbilirubinaemia, or in cats with hyperlipidaemia or azotaemia.