博威钙预防奶牛产后低血钙的效果观察

高产奶牛产后亚临床低血钙的发病率40.74%,凭借自身钙调节能力无法在产后24h将血液离子钙恢复正常水平.博威钙对奶牛血液有轻微的酸化作用,可增强钙动员调节机制,奶牛在产后0h、12h两次投服博威钙,能明显提高血液中离子钙水平,对奶牛产后低血钙有很好的预防作用.     

Effects of dietary cation-anion difference on blood cortisol and ACTH levels in reproducing ewes

Formulation of rations to induce a compensated metabolic acidosis in the post-partum cow has proved a useful strategy for prevention of milk fever. Such acidification improves the ability of the animal to maintain calcium homeostasis by promoting the absorption of calcium from the intestine and mobilization of calcium from the bone. In humans, an acidogenic diet results in mild metabolic acidosis in association with a state of cortisol excess and this increase in plasma cortisol may increase bone catabolism. The objective of our experiment was to induce acidification by anionic salt supplementation and to study the effects of anionic supplementation on plasma cortisol and adrenocorticotropic hormone (ACTH) levels in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and +164.5 mEq/kg DM respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks pre-partum and continuing until 12 days post-partum. Anionic diet induced a non-respiratory systemic acidosis in association with a mild increase in plasma cortisol concentration without changes in plasma ACTH levels. Our data suggest that the mild hypercortisolism observed in sheep fed the anionic diet may not be an effector for bone resorption induced by anionic salts. A mild hypercortisolism of this magnitude may lead to osteoporosis but this might require many years of adrenal hypersecretion while anionic salts are only used during the last weeks of pregnancy.     

Electromyographic changes of motor unit activity in horses with induced hypocalcemia and hypomagnesemia

OBJECTIVE: To determine whether electromyographic abnormalities are evident in skeletal muscles in horses with induced hypocalcemia and hypomagnesemia. ANIMALS: 7 healthy adult Dutch Warmblood horses. PROCEDURES: Electromyographic examination was performed in the lateral vastus, triceps, and subclavian muscles before and after IV infusion of EDTA. An initial dose (mean +/- SD, 564+/-48 ml) of a 10% solution of sodium EDTA was administered IV during a period of 21+/-73 minutes to establish a blood concentration of ionized calcium of approximately 0.5 mmol/L. Average rate of EDTA infusion to maintain ionized calcium at this concentration was 6.6 ml/min. RESULTS: Mean blood concentrations of ionized calcium and magnesium were 1.39+/-0.06 and 0.84+/-0.09 mM, respectively before EDTA infusion; after EDTA infusion, concentrations were 0.48+/-0.05 and 0.44+/-0.20 mM, respectively. This state induced positive waves; fibrillation potentials; doublets, triplets, and multiplets; complex repetitive discharges; and neuromyotonia. Analysis of motor unit action potentials (MUAP) after EDTA infusion revealed an increase in prevalence of polyphasic and complex MUAP in all muscles. CONCLUSIONS AND CLINICAL RELEVANCE: None of the horses had classical signs of hypocalcemia and hypomagnesemia. In contrast, all horses had spontaneous activity in the measured muscles indicative of nerve hyperirritability. Calcium and magnesium deficits appear to have consequences, which may be subclinical, affecting functions of the neuromuscular system. This is of interest for equestrian sports in which hypocalcemia and hypomagnesemia are expected, such as during endurance rides.     

Effect of pre-calving zeolite, magnesium and phosphorus supplementation on periparturient serum mineral concentrations

The objective of this study was to test whether supplementing dry cow rations with phosphorus (P) and magnesium (Mg) would interfere with the beneficial effect of zeolite supplementation on the periparturient blood calcium (Ca) concentration in dairy cattle. Three groups (A-C) of 10 Danish Jersey cows were each given the following daily supplements from 2 weeks before the expected date of calving until actual calving: group A: zeolite, monoammonium phosphate, standard dry cow mineral and vitamin mix, containing 61g magnesium phosphate; group B: zeolite, standard mineral and vitamin mix without the magnesium phosphate and group C: standard mineral and vitamin mix, monoammonium phosphate. All cows in group B had an apparently less variable serum calcium concentration around calving with no cases of milk fever and no subclinical hypocalcaemia or hypomagnesaemia recorded. In contrast, a parturient drop in blood Ca was seen in group A as well as group C. In group A, one cow was hypocalcaemic at calving, and developed milk fever. In group C, 12 blood samples, representing six cows, were hypocalcaemic, and three of these cows were treated for milk fever. All groups remained normomagnesaemic and there were no significant differences in blood Mg across groups. In conclusion, the combined P and Mg supplementation in addition to zeolite supplementation did not increase the serum Mg level (forage Mg 16.9g/day; 0.21% of DM). Combined P and Mg supplementation reduced the zeolite-induced hypophosphataemia but also reduced the stabilising effect of zeolite on parturient serum Ca.     

阴离子型日粮及补Ca对围产期奶牛代谢与健康及其生产性能的影响

将36头干奶后期中国荷斯坦奶牛随机分为对照组、试验Ⅰ组、试验Ⅱ组（每组12头）．分别饲喂常规日粮、阴离子型日粮及在此基础上朴Ca日粮，探讨其对奶牛体内代谢状况、健康状况及生产性能的影响。与饲喂常规日粮相比，饲喂阴离子型日粮可降低奶牛尿液pH值（P〈0．01）和血液HCO2^-浓度（P〉0．05）；增加奶牛产后12h（P〈0．05）、2d（P〈0．05）血清总钙含量．对血清无机磷、镁含量没有显著影响；明显降低奶牛亚临床性低血钙率（33％）、胎衣不下率（33％）和乳房水肿率（17％）；增加牛奶乳糖率（P〈0．05），对其他奶成分和奶产量没有显著影响（P〉0．05）。在阴离子型日粮中补Ca后．与饲喂阴离子型日粮相比．除增加奶牛产后血清镁含量外（P〈0．05）．对其他各项指标没有明显影响。     

Milk fever in dairy cows: a review of pathophysiology and control principles

The periparturient or transition period of 4 weeks before and 4 weeks after calving is characterised by a greatly increased risk of disease. Hypocalcaemia around calving is a risk factor for many of these diseases and is an indirect risk factor for increased culling. The incidence of clinical hypocalcaemia (milk fever) in the field generally ranges from 0-10%, but may exceed 25% of cows calving. In research trials conducted on milk fever the incidence has approached 80% of cows calving. Homeostasis of calcium (Ca) is regulated by calcitonin, parathyroid hormone and 1,25(OH)(2) vitamin D(3). Age increases the risk of milk fever by approximately 9% per lactation. Control of milk fever has revolved around stimulation of homeostatic mechanisms through feeding a pre-calving diet low in Ca. More recently, the role of the dietary cation anion difference (DCAD) in the prevention of Ca disorders has been examined, both by field research and meta-analysis. The most appropriate form of the DCAD equation has been contentious, but recent meta-analyses have shown that the equation (Na(+)+K(+))-(Cl(-)+S(2-)) is most effective for predicting milk fever risk. Decreased risk of milk fever is linear with DCAD, whereas the effect of DCAD on urinary pH is curvilinear. A pivotal role of providing dietary magnesium (Mg) before calving has been confirmed by meta-analysis, and a quadratic effect of Ca on milk fever risk was found with a peak occurring with dietary levels of 1.1-1.3% of dry matter. Risks of milk fever increase with increased dietary phosphorus (P) fed pre-calving and with increasing days of exposure to a pre-calving diet. Meta-analysis has revealed that the important roles of dietary Ca, Mg and P, as well as the duration of exposure to the pre-calving diet in milk fever control strategies are independent of DCAD. Studies on the effect of exposure to well designed pre-calving diets have shown that substantial improvements in production, reproduction and animal health can be made but further examination of the influence of the period of exposure to different diets is warranted.     

Studies on parturient paresis with special reference to the Downer cow syndrome

In addition to the classic form of parturient paresis characterized by hypocalcemia and somnolence, which responds rapidly to calcium therapy, it is not unusual to encounter other forms of this disease. The most common aberration would seem to be that in which the animals do not rise after calcium treatment. Many of these cows show little or no drowsiness, their appetite is often good, and the results of a clinical examination often negative. Some authors, Blood & Henderson (1960) for instance, consider that this “downer cow syndrome” is an indépendant disease not connected wiht milk fever.Although the downer cow syndrome is a common disease and is of considerable significance, remarkably little has been written about it. Garm in 1950 noted that the frequency of downers had increased as compared with the numbers registered a few years earlier. He had also noticed that in many of these cows hypocalcemia was present on the first day of illness but not on subsequent days, despite the fact that they had marked signs of milk fever. Osinga, in an investigation in 1963, compared two types of milk fever: a typical form in which the cow is drowsy, lies on her side, and has partial anorexia, and an atypical form in which the animal is alert and has normal or only slight loss of appetite. Osinga remarked that the atypical cases had in-creased in number and suggested as an explanation the fact that the amount of protein in the fodder has increased, with the result that auto-intoxication and damage to parenchymatous organs may occur.The object of the present investigation was to study the difference between cows that recover after treatment (“uncomplicated milk fever”) and those that have not risen 24 hrs. after the first treatment (“downers”). We also wanted to ascertain whether any changes occurred in the downers between the first and second, and second and third days. In addition, the difference between cows with blood-calcium levels equivalent to or over 8.0 mg/100 ml serum and those with corresponding values under 8.0 mg at the first examination was also studied.     

向日葵副产物的营养特性及在反刍动物中的应用

饲料资源缺乏一直以来都是制约中国畜牧业发展的主要因素。从长远看，常规饲料已不能维持中国畜牧业的可持续发展，开发新的饲料资源是解决饲料不足的重要途径之一。向日葵副产物营养价值较高、来源广、价格低，是一种非常具有开发价值的新型饲料。向日葵副产物包括向日葵饼粕、向日葵盘、向日葵秸秆及葵花籽壳：向日葵饼粕蛋白质含量高、纤维含量低，是一种优质的植物蛋白来源，可以提高奶牛乳汁的营养价值、促进肉牛生长、提高羊的瘤胃发酵效果；向日葵盘粗脂肪含量高，含有大量的膳食纤维，可以提高奶牛的产奶量和乳脂率，促进肉牛增重，提高羊瘤胃挥发性脂肪酸浓度以及粗蛋白质、粗纤维、中性洗涤纤维的消化率；向日葵秸秆富含氮、磷、钾、钙、镁等矿物质元素以及少量的蛋白质，可以为肉牛提供一些常量元素和微量元素，提高羊的日增重，降低料重比；葵花籽壳的主要成分是纤维素和木质素，含有丰富的生物活性物质，可以提高奶牛日增重、肉牛饲料转化率。作者具体介绍了向日葵副产物饼粕、葵盘、秸秆、葵花籽壳的营养价值，以及目前它们在反刍动物饲料中的应用情况，以期为今后向日葵副产物的开发利用提供理论依据。     

Hypomagnesemia and hypocalcemia associated with protein-losing enteropathy in Yorkshire terriers: five cases (1992-1998)

OBJECTIVE: To determine clinical and laboratory findings associated with protein-losing enteropathy, hypomagnesemia, and hypocalcemia in Yorkshire Terriers. DESIGN: Retrospective study. ANIMALS: 5 purebred or crossbred Yorkshire Terriers with protein-losing enteropathy, hypomagnesemia, and hypocalcemia. PROCEDURE: Medical records were reviewed for dogs with protein-losing enteropathy, hypomagnesemia, and hypocalcemia. RESULTS: Of 8 dogs with these signs, 5 had Yorkshire Terrier breeding. Common findings were diarrhea, abdominal effusion, leukocytosis, neutrophilia, hypocalcemia (ionized calcium), hypomagnesemia, hypoproteinemia, hypoalbuminemia, hypocholesterolemia, and increased serum activity of aspartate aminotransferase. CONCLUSIONS AND CLINICAL RELEVANCE: Yorkshire Terriers are at increased risk for development of protein-losing enteropathy with hypomagnesemia and decreased ionized calcium concentration. Hypomagnesemia and hypocalcemia may have a related pathogenesis involving intestinal loss, malabsorption, and abnormalities of vitamin D and parathyroid hormone metabolism. Serum electrolyte replacement may be required to avoid neurologic and metabolic problems.     

Prevalence and prognostic importance of hypomagnesemia and hypocalcemia in horses that have colic surgery

OBJECTIVE: To determine the prevalence of hypomagnesemia and hypocalcemia in horses with surgical colic. ANIMALS: 35 horses with surgically managed colic. PROCEDURE: Serum concentrations of total magnesium (tMg2+) and calcium (tCa2+), as well as ionized magnesium (iMg2+) and calcium (iCa2+) were analyzed before surgery and 1, 3, 5, and 7 days following surgery. A lead-II ECG and pertinent clinical data were also obtained at each time. RESULTS: Preoperative serum tMg2+ and iMg2+ concentrations were below the reference range in 6 (17%) and 19 (54%) horses, respectively. Serum concentrations of tCa2+ and iCa2+ were less than the reference range in 20 (57%) and 30 (86%) horses before surgery. Horses with strangulating lesions of the gastrointestinal tract had significantly lower preoperative serum concentrations of iMg2+ and iCa2+, as well as a higher heart rate than horses with nonstrangulating lesions. Horses that developed postoperative ileus had significantly lower serum concentrations of iMg2+ after surgery. Serum concentrations of magnesium and calcium (total and ionized) correlated significantly with the PR, QRS, QT, and corrected QT (QTc) intervals. Horses that were euthanatized at the time of surgery (n = 7) had significantly lower preoperative serum concentrations of iMg2+, compared with horses that survived. Neither serum magnesium nor calcium concentrations were predictors of hospitalization time or survival. CONCLUSIONS AND CLINICAL RELEVANCE: Hypomagnesemia and hypocalcemia were common during the perioperative period, particularly in horses with strangulating intestinal lesions and ileus. Serum concentrations of tMg2+ and tCa2+ were less sensitive than iMg2+ and iCa2+ in detecting horses with hypomagnesemia and hypocalcemia.     

Historical and current perspectives on the treatment, control and pathogenesis of milk fever in dairy cattle

Milk fever has been recognised in cattle for about 215 years and its clinical signs have not changed since they were described by Victorian veterinary surgeons in the mid-nineteenth century. It was only 80 years ago that abnormal parathyroid gland function was associated with the pathogenesis of the hypocalcaemia characteristic of the disease, and the current basis for its treatment with intravenous calcium salts was established. Although this treatment is effective, most recent research has focused on preventing the disease through an understanding of the endocrine control of extracellular calcium homeostasis. In the 1970s the synthetic vitamin D analogue 1alpha-hydroxycholecalciferol was developed for intramuscular injection before a cow calved, but variable results encouraged other preventive strategies to be considered, including restricting the dietary intake of calcium, and manipulating the dietary cation-anion balance of cows before they calved. Currently, the role of extracellular calcium receptors in the parathyroid gland is under investigation as a preliminary step to devising more effective treatments and/or preventive methods for milk fever.     

The effectiveness of cholecalciferol and flumethasone for the prevention of hypocalcemic parturient paresis in dairy cows]

Investigations on the efficacy of high doses of cholecalciferol and flumethasone for prophylaxis of hypocalcemic milk fever were performed in dairy cows. Only one cow in the group of 25 treated animals diseased by milk fever, but 5 of 25 control animals showed signs of hypocalcemia. A placenta retention was observed in three treated animals and in four control animals. The results show that the additional application of flumethasone for birth induction after the injection of vitamin D3 was unchanged.     

Feeding 5-hydroxy-l-tryptophan during the transition from pregnancy to lactation increases calcium mobilization from bone in rats

An increasing demand for calcium during pregnancy and lactation can result in both clinical and subclinical hypocalcemia during the early lactation period in several mammalian species, in particular the dairy cow. Serotonin (5-HT) was recently identified as a regulator of lactation and bone turnover. The purpose of this study was to determine whether supplementation of the maternal diet with a 5-HT precursor would increase maternal bone turnover and calcium mobilization to maintain appropriate circulating maternal concentrations of ionized calcium during lactation. Female Sprague-Dawley rats (n = 30) were fed either a control diet (n = 15) or a diet supplemented with the 5-HT precursor 5-hydroxytryptophan (5-HTP, 0.2%; n = 15) from day 13 of pregnancy through day 9 of lactation. Maternal serum and plasma (day 1 and day 9 of lactation), milk and pup weight (daily), mammary gland and bone tissue (day 9 of lactation) were collected for analysis. The 5-HTP diet elevated circulating maternal concentrations of 5-HT on day 1 and day 9 of lactation and parathyroid hormone related-protein (PTHrP) on day 9 of lactation (P < 0.033). In addition, 5-HTP supplementation increased total serum calcium concentrations on day 1 of lactation and total milk calcium concentration on day 9 of lactation (P < 0.032). Supplemental 5-HTP did not alter milk yield, maternal body weight, mammary gland structure, or pup litter weights (P > 0.05). Supplemental 5-HTP also resulted in increased concentrations of mammary 5-HT and PTHrP, as well as increased mRNA expression of rate-limiting enzyme in 5-HT synthesis, tryptophan hydroxylase 1, and Pthrp mRNA on day 9 of lactation (P < 0.028). In addition, supplementation of 5-HTP resulted in increased mRNA expression of maternal mammary calcium transporters and resorption of bone in the femur, indicated by increase osteoclast number and diameter as well as mRNA expression of classical markers of bone resorption on day 9 of lactation (P < 0.048). These results show that increasing 5-HT biosynthesis during the transition from pregnancy to lactation could be a potential therapeutic target to explore for prevention of subclinical and clinical hypocalcemia.     

Management of dry cows for the prevention of milk fever and other mineral disorders.

Mineral disorders in dairy cattle typically occur soon after calving and are often specifically related to nutritional management during the late dry period. The incidence of hypocalcemia, hypophosphatemia, and hypomagnesemia can be minimized by proper diet formulation and good overall nutritional management in the dry period. The addition of anions to the diet during the late dry period may be of particular benefit for preventing hypocalcemia; however, supplementation with anions will reduce dry matter intake if feeding management is not excellent.     

Milk fever control principles: a review

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%-60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K)-(Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.     

Definition of a non-alert downer cow syndrome and some case histories

The clinical, blood biochemical and autopsy findings on a cow affected by a 'non-alert downer cow syndrome' are described in detail and compared with brief clinical and biochemical details from six similar cases attended elsewhere. The significance of the biochemical observations is discussed in relation to the observations from many other clinical milk fever cases in a dairy practice in Victoria. This syndrome developed in 1.9 per cent of 584 cases of milk fever. The essential findings in the syndrome were that all cows had an initial clinical episode suggestive of milk fever but showed an unsatisfactory clinical response to calcium borogluconate therapy. After a day or two all cows became laterally recumbent, some exhibited expiratory moaning and all developed mucoid faeces which, in many cases contained spots of blood. All cases had significantly lower erythrocyte and plasma potassium concentrations than those in milk fever cases which responded to treatment.     

Macromineral disorders of the transition cow.

Four macrominerals have the distinction of being involved in the "downer cow" syndrome, which is, unfortunately, often associated with parturition in cows. Inadequate blood calcium (Ca), phosphorus (P), magnesium (Mg), or potassium (K) concentrations can cause a cow to lose the ability to rise to her feet because these minerals are necessary for nerve and muscle function. Less severe disturbances in blood concentrations of these minerals can cause reduced feed intake, poor rumen and intestine motility, poor productivity, and increased susceptibility to other metabolic and infectious disease. Mechanisms for maintaining blood Ca, P, Mg, and K concentrations perform efficiently most of the time, but occasionally these homeostatic mechanisms fail and metabolic diseases such as milk fever occur. Understanding how and why these mechanisms fail may allow the practitioner to develop strategies to avoid these disorders.     

水牛乳和荷斯坦牛乳中五种常量元素含量的测定

对摩本杂水牛(摩拉水牛×德宏水牛)乳和荷斯坦牛乳中的5种常量元素进行测定.采用火焰光度法测定钾、钠含量,火焰原子吸收分光光度法(FAAS)测定钙、镁含量,磷钼酸比色法测定磷含量.结果表明,水牛乳中钾、钠含量极显著低于荷斯坦牛乳(P<0.01),钙、磷含量极显著高于荷斯坦牛乳(P<0.01),两种牛乳中镁含量差异不显著(...     

奶牛产乳热影响因子及预防措施

产乳热是奶牛产犊后泌乳造成血钙水平下降而引发的营养代谢性疾病，其发生病率非常高，对奶牛健康和生产性能影响较大。产乳热增加了奶牛生育性炎症、生殖障碍和内分泌、消化等方面疾病发生的几率，对养殖业造成很大的损失。影响奶牛产乳热的因素有很多，不仅包括奶牛品种、年龄、体况评分、产乳热史等牛自身因子，也包括饲养管理层面的因素，如泌乳天数、干奶期、产犊间隔的控制及奶牛饲料营养水平的调控，还与气候、环境等外界因素相关，这些影响因子往往相互交织，增加了奶牛产乳热的预防和治疗难度。作者综述了奶牛产乳热的发病机理，分析研究了各种因子对奶牛产乳热的影响机制，并介绍了几种预防措施，主要包括对奶牛饲养环境的管理、产犊间隔和泌乳情况的控制和奶牛不同阶段饲料营养水平的调控，以期为降低奶牛产乳热提供理论依据。     

A comparison of total calcium,corrected calcium,and ionized calcium concentrations as indicators of calcium homeostasis among hypoalbuminemic dogs requiring intensive care

Objective – (1) To evaluate whether total calcium (tCa) correlates with ionized calcium (iCa) in hypoalbuminemic dogs; (2) to evaluate whether calcium adjusted for albumin (Alb), or total protein (TP), or both accurately predict iCa concentrations and hence can be used to monitor calcium homeostasis in critically ill hypoalbuminemic dogs; and (3) to evaluate factors associated with any potential discrepancy in calcium classification between corrected total and ionized values. Design – Prospective observational clinical study. Setting – Small animal intensive care unit in a veterinary medical teaching hospital. Animals – Twenty‐eight client‐owned dogs with hypoalbuminemia. Interventions – None. Measurements and Main Results – iCa was determined using ion‐specific electrode methodology, on heparinized plasma. The tCa concentration was adjusted for Alb and TP using published equations. In total 29% (8/28) of the hypoalbuminemic, critically ill dogs in this study were hypocalcemic at intensive care unit admission, as determined by iCa measurement. Corrected calcium values failed to accurately classify calcium status in 67.9% and 64.3% of cases, according to whether the Alb‐adjusted or TP‐adjusted values, respectively, were used. The sensitivity and specificity of the tCa to evaluate hypocalcemia was 100% and 47%, respectively. The sensitivity and specificity of the correction formulae were 37.5% and 79% for the Alb‐adjusted values and 37.5% and 74% for TP‐adjusted values. tCa overestimated the presence of hypocalcemia and underestimated the presence of normocalcemia, while corrected calcium values overestimated the presence of normocalcemia and underestimated the presence of hypocalcemia. Conclusions – Calcium homeostasis in hypoalbuminemic critically ill dogs should be evaluated by iCa concentrations rather than tCa or calcium adjusted for Alb or TP. Given that tCa has 100% sensitivity for detecting hypocalcemia in this population it is recommended that all hypoalbuminemic and critically ill patients with low tCa should be evaluated with an iCa measurement.