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Hypocalcaemia prevention programmes have been widely studied in experimental settings, but their feasibility has not been assessed under field conditions. The main objective of this study was to evaluate, in the context of small dairy farms in western France, whether and how dairy farmers implement prevention programmes and manage the feeding of dry cows to prevent hypocalcaemia. Seventy-nine commercial Holstein dairy farms in Brittany (France) were enrolled in a qualitative study in 2019. We conducted in-person interviews with the farmers to 1) understand the rationale behind the type and seasonality of prevention programmes they implemented and 2) assess how closely they followed common recommendations when implementing them. Most farmers (80 %) used at least one prevention programme, especially supplying a mineral mix formulated to meet the needs of dry cows in late gestation (53 %), acidifying the diet in late gestation (37 %), and supplying calcium at calving (oral or injectable form, 37 %). The use of programmes depended on whether the diet composition varied throughout the year. Among farmers who provided an acidified diet, 25 % did not supply a specific mineral mix to dry cows to ensure an adequate amount of P, Ca, and Mg, which could decrease the effectiveness of the acidification programme. A lack of reliability in feeding practices, such as not weighing feed or not delivering feed frequently enough, was identified for 61 % of contributing farms. Management practices could result in supplying an unsuitable amount of P, Ca, or Mg immediately before calving; for example, inappropriate batching practices around calving were identified for 22 % (cows) to 32 % (heifers) of farms. In addition, nearly all contributing farmers had no processes in place to monitor the effectiveness of the programmes implemented. Reasons for this overall lack of compliance should be explored., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Hypocalcemia remains a common metabolic disorder of dairy cattle; therefore, an efficient prevention is still challenging. Among the various prevention strategies for hypocalcemia is the use of anionic compounds to induce a mild metabolic acidosis during the prepartum period. Acid-base status can be readily assessed through urine pH. Accordingly, a target urine pH during the prepartum period between 6.0 and 6.8 has been recommended for Holstein cows; however, in several countries, including the US, certain nutritional strategies are still focused on benchmarking the urine pH to below 6.0. Unfortunately, over-acidification can have no advantages and/or detrimental effects on both the dam and her offspring. In this review, updated information regarding the use of anionic diets on prepartum dairy cows and the potential negative impact of such diets on both cow and calf performance are discussed. There is an urgent need for studies that will elucidate the pathophysiological mechanisms by which very acidotic diets may impact the well-being and productive efficiency of dairy cows, and the transgenerational effects of such diets on offspring performance and survival., (Copyright © 2022 Texas Tech University. Published by Elsevier B.V. All rights reserved.)

Periparturient hypocalcaemia is a widespread metabolic disorder in dairy cows. Clinical and subclinical cases occur primarily in multiparous (Multi) cows, but subclinical cases have also been reported in primiparous (Primi) cows. A preventive strategy was investigated by administering the physiologically active vitamin D 3 metabolite, 1,25-dihydroxyvitamin D 3 (1,25-dihydroxycholecalciferol, 1,25(OH) 2 D 3 ) as a rumen bolus. The bolus contained tablets of 1,25(OH) 2 D 3 glycoside extract from Solanum glaucophyllum (SGE), releasing SGE over several days. The aim was to study the effect of a bolus containing 0 (C) or 500 µg (SGE) of 1,25(OH) 2 D 3 on 1,25(OH) 2 D 3 and mineral status in periparturient cows up to three weeks into lactation and on colostrum, milk and calves' blood mineral contents. The bolus was administered three to four days prior to expected calving to Primi and Multi cows fed a herbage-based diet (dietary cation-anion difference of +522 mEq/kg DM). One C or SGE bolus was applied to 12 Primi and 12 Multi cows. Blood was regularly sampled (and selected a posteriori for antepartum samples) in regard to the actual calving day (d0), immediately prior to bolus application and at day -2, 0.5, 1, 1.5, 2, 4, 8, 11, 15, 18 and 22. Additional samples included urine (at bolus application, d0.5 and d2), colostrum, milk samples (weekly) and calves' blood (d2). Blood serum 1,25(OH) 2 D 3 increased between d0.5 and d2 in Primi-SGE, but remained unchanged in Primi-C, as did parathyroid hormone (PTH) and Ca in all Primi. Urinary Ca of Primi-SGE was increased on d2, indicating regulation of Ca excess. Three Multi-C cows with confirmed clinical hypocalcaemia needed treatment and thus were excluded from the dataset and replaced. Blood serum 1,25(OH) 2 D 3 and PTH increased while Ca dropped by 40% between d0.5 and d2 in Multi-C, whereas 1,25(OH) 2 D 3 , Ca and PTH remained unchanged in Multi-SGE. Blood serum carboxyterminal telopeptide of type I collagen was higher in Primi than in Multi and increased with time, except in Primi-C. Mineral contents in colostrum, milk and blood serum of calves were not influenced to a relevant degree. In conclusion, Primi-C did not, in contrast to Multi-C, develop subclinical hypocalcaemia (<2.0 mmol Ca/l). Prevention of hypocalcaemia with one SGE bolus applied three to four days prior to expected calving was successful in maintaining blood Ca within normal range in Multi over the critical first two days and up to the first three weeks of lactation, without any observed detrimental effects on cows or calves., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Objective: The most common complication after thyroid surgery is hypocalcaemia and it sometimes leads to problems that are difficult to correct in patients. The present study was aimed to determine the risk factors causing the development of hypocalcaemia after thyroid surgery., Methods: 818 adult patients were included in the study. The data were recorded by examining the hospital automation system and patient files retrospectively. Patients' demographic characteristics, radiological imaging findings, serum biochemical parameters, extent of the performed surgery, histopathological diagnoses were recorded., Results: The rate of hypocalcaemia was 28.4% (1.7% permanent). In multivariate analysis: the female gender (p = 0.002), heavier thyroid gland (p = 0.084), substernal location (p = 0.004) and cervical lymph nodes dissection (CLND) (p < 0.001) were found to be significantly. Malignant thyroid pathology (p = 0.006) and total thyroidectomy (p = 0.025) increased the risk of hypocalcaemia significantly in univariate analysis. However, this increase in risk was not found to be statistically significant in regression analysis. Significant statistical result was not found on postoperative hypocalcaemia in terms of advanced age, hyperthyroidism and re-operation. The duration of hospitalization was higher in patients with postoperative hypocalcaemia (m = 2 days) (p < 0.001)., Conclusion: In our analyses CLND, female gender, substernal location and heavier thyroid gland was found to be the independent risk factors in the development of postoperative hypocalcaemia. The development of postoperative hypocalcaemia may be predicted and measures may be taken to prevent clinical findings., (Copyright © 2019. Published by Elsevier Taiwan LLC.)

Vitamin D plays a key role in calcium-phosphorus homeostasis and bone metabolism, but it is also involved in numerous others tissues. Vitamin D deficiency among pregnant women is frequent in many populations over the world. It is associated with an increased risk of preeclampsia, gestational diabetes mellitus, and caesarean section. Consequences in newborns are low birth weight, neonatal rickets, a risk of neonatal hypocalcemia, asthma and/or type 1 diabetes. Therefore, prevention of vitamin D deficiency among pregnant women is essential. The currently recommended supplementation amount of vitamin D is not sufficient to maintain a value of 25 hydroxy vitamin D above 30 ng/ml, during pregnancy. Randomized controlled trials during pregnancy are necessary to evaluate the amount of vitamin D sufficient to avoid the consequences of vitamin D deficiency., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Mice lacking 25-hydroxycholecalciferol [25(OH)D]-1alpha-hydroxylase (CYP27B1) are growth retarded, hypocalcemic, and have poor bone mineralization. We tested whether high dietary cholecalciferol (VD3) could exert effects in the absence of CYP27B1 in vivo. Weanling male wild-type (WT) and CYP27B1 knockout (KO) mice were fed either a 2% calcium (Ca), 20% lactose rescue diet or an AIN93G diet (0.5% Ca, 0.4% phosphorus) containing 1000 (1K, the rodent requirement, 25 microg), 10,000 (10K, 250 microg), or 20,000 (20K, 500 microg) IU VD3/kg diet until 12 wk when blood and tissues were taken. Serum 25(OH)D was >90 nmol/L in the 1K diet group and increased >4-fold in mice fed 10K and 20K diets. The 1K diet impaired growth and caused hypocalcemia in KO mice; the 10K and 20K diets were as effective as the high Ca rescue diet in preventing these outcomes. High VD3 restored expression of vitamin D-regulated genes in intestine (calbindin D(9K)) and kidney (CYP27B1, 24-hydroxylase, calbindin D(9K)) of KO mice. Micro-computed tomography of femora revealed complete recovery of cortical bone in KO mice fed either the rescue or 10K diets but only partial recovery of trabecular bone measures (e.g. 40% lower bone volume, 20% lower trabecular thickness, and 23% increase in trabecular separation). These data show that very high serum 25(OH)D can influence Ca and bone metabolism independent of its conversion to 1,25 dihydroxycholecalciferol. However, neither high dietary Ca nor high dietary VD3 is sufficient to fully recover the phenotype of CYP27B1 KO mice.

Aim: This study aimed to evaluate hypocalcaemia (time-course) and need for calcium administration after thyroid surgery in 135 consecutive cases (69 bilateral subtotal thyroidectomies, 50 unilateral lobectomies, 13 total thyroidectomies and three isthmectomies) for benign lesions and for differentiated carcinoma in 89% and 11% respectively., Results: In unilateral lobectomy, two parathyroid glands were identified and preserved in 72%, and one gland in 28% of the patients; calcaemia decreased by 10% on average in the early post-operative period (P<0.001). Calcium treatment (average: 2.3 days) was administered to 34% of the patients, these patients had lower nadir post-operative calcaemia than those who did not receive calcium: 2.03 vs 2.14 mmol/l (P<0.001). Their calcaemias reverted to normal within 1 week after surgery and remained normal thereafter without further calcium administration. In bilateral procedures, four parathyroid glands were preserved in 40%, three in 42%, two in 16%, and only one in 2% of the cases. Calcaemia decreased by 15% on average (P<0.001), and early hypocalcaemia was common and severe in some patients: nadir post-operative calcaemia <2.0 mmol/l in 61%, and <1.75 mmol/l in 6% of the cases. Post-operative hypocalcaemia was more pronounced after total than subtotal thyroidectomy (1.86+/-0.19 vs 1.98+/-0.14 mmol/l P=0.014), and also after lymph node dissection (1.83+/-0.11 mmol/l). Serum parathormone (PTH) decreased from 36 ng/l before surgery to 17 ng/l in the week thereafter (P=0.001). There was a linear relationship between the number of preserved parathyroid glands and early hypocalcaemia. The percentage of patients requiring calcium treatment was: 24 h (15%), 2-7 days (26%), 8-180 days (33%), >1 year (9%)., Discussion: The number of parathyroid glands preserved in situ did not help predict the duration of post-surgical calcium treatment, nor the final outcome of hypocalcaemia. However, when total calcium levels were compared in patients having had one or two glands preserved vs three or four parathyroid glands, it was possible to show that despite prolonged calcium administration, late calcaemias remained significantly lower during the first 6 months in patients with a smaller number of parathyroid glands. Hypoparathyroidism, defined functionally on the basis of requirement of calcium supplementation 1 year after surgery, occurred in 8.6% of patients after bilateral lobectomy (despite measurable but inappropriately low-PTH concentration). This outcome could have been predicted earlier (after 3 to 6 months) and the patients perhaps given the benefit of definitive vitamin D treatment earlier, in order to avoid late and prolonged hypocalcaemia. Evaluation after 1 year showed that only one patient out of 82 bilateral lobectomies (1.2%) had permanent hypoparathyroidism and needed calcium whereas hypocalcaemia was persistent in one out of four patients who had undergone a staged procedure (i.e. heterolateral lobectomy years after a previous operation)., (Copyright 2000 Harcourt Publishers Ltd.)

To determine the relevance of circulating 1,25-dihydroxycholecalciferol [1,25(OH)2D3] to the pathogenesis of hypocalcemia during magnesium deficiency, growing chicks were pair fed control or Mg-deficient diets with or without 1,25(OH)2D3 supplementation. Within 14 d, chicks fed the Mg-deficient diet without 1,25(OH)2D3 supplementation exhibited hypomagnesemia and hypocalcemia compared to control chicks. 1,25-Dihydroxycholecalciferol supplementation in Mg-deficient chicks elevated plasma 1,25(OH)2D3 twofold and increased plasma calcium to control levels. Supplementation with 1,25(OH)2D3 did not increase plasma Mg concentration in Mg-deficient chicks, indicating that exogenous 1,25(OH)2D3 prevented hypocalcemia in the absence of greater Mg availability. Magnesium-deficient chicks supplemented with 1,25(OH)2D3 had more intestinal calbindin D-28K relative to Mg-deficient nonsupplemented chicks, suggesting that increased absorption of dietary Ca may have contributed to the greater plasma Ca concentration in 1,25(OH)2D3 supplemented Mg-deficient chicks. Although clinical hypomagnesemia has been associated with vitamin D resistance, our data indicate that primary Mg deficiency did not impair target tissue responsiveness to 1,25(OH)2D3, at least at the level of the intestine. Supplementation with 1,25(OH)2D3 did not increase bone Mg concentration and did not alter the characteristic skeletal morphology. It also did not increase bone Ca concentration in Mg-deficient chicks. The data suggest that skeletal alterations during Mg deficiency result from hypomagnesemia per se, rather than hypocalcemia or insufficient 1,25(OH)2D3.

Serum levels of 25-hydroxyvitamin D [25-(OH)D], calcium, phosphate and alkaline phosphatase activity were measured between December and July in 110 pregnant women during the last trimester of pregnancy, and in their infants on the fifth day of life. This study showed a fall, during spring, below 6 ng/ml, of the maternal 25-(OH)D concentration at the time of delivery, and a fall of the 25-(OH)D and calcium concentrations in newborns. The existence of a positive correlation between calcium and 25-(OH)D levels in the newborns suggests that the low calcium concentrations found in the infants born in spring is related to a vitamin D deficiency of the infant and therefore of the mother. The administration of a single low dose of vitamin D3 (100,000 I.U.) on the sixth or seventh month of pregnancy allowed to prevent the seasonal fall in serum calcium and 25-(OH)D concentrations. This dosage appears therefore to be sufficient to reduce the risk of vitamin D deficiency of the newborn and the occurrence of neonatal hypocalcemia.

The supplementation of replacement solutions used during plasma exchange with calcium gluconate prevents hypocalcaemic symptoms.