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At least 37 records · Page 2Linked to original sources
PubMed1983

Wheat pasture poisoning. II. Tissue composition of cattle grazing cereal forages and related to tetany.

Thirty-two aged Hereford and Angus cows (avg 10.2 yr old) grazed mixed cereal (wheat and rye) pastures from December 6, 1979 to April 23, 1980 (138 d). On d 104 (March 19), five cows developed tetany. On the day of tetany, the mean plasma Ca of the cows with tetany was 4.1 mg/dl. Cows with tetany had plasma Mg concentrations of 1.7 mg/dl on the day of tetany, but 15 d before tetany and 6 d post-tetany, levels were lower (1.2 mg/dl). Cows with tetany had large increases in plasma parathyroid hormone (PHT) as well as vitamin 1, 25 dihydroxy D3 [1,25(OH)2D], plasma glucose, lactic acid and beta-hydroxybutyric acid. Plasma K of these cows followed a similar trend as plant K, except it was not as pronounced. Plasma inorganic P of these same cows was exceedingly low, less than 3 mg/dl several times, although the forage P did not indicate a P deficiency. Levels of plasma hydroxyproline in these cows indicated that bone resorption may have been low during most of the grazing season, even though levels of plasma hydroxyproline were initially high and high subsequent to tetany. High levels of plasma glucose and lactic acid were associated with the time of tetany. Apparently, cows developed inappetence around the time of tetany, as suggested by the high levels of plasma beta-hydroxybutyric acid. Cows with wheat pasture poisoning appeared to respond to the severe hypocalcemia with large increases in plasma 1,25(OH)2D. Plasma 1,25(OH)2D changes were similar to plasma hydroxyproline changes (and possible bone resorption rates) and seemed inversely proportional to plasma Ca and directly proportional to plasma PTH concentrations. Generally, cerebrospinal fluid (CSF) composition was not affected as much as plasma composition, except for the low levels of CSF Ca. These data indicate that a metabolic deficiency of Ca (hypocalcemia) was the cause of tetany.

3-Hydroxybutyric Acid↗
PubMed1983

Wheat pasture poisoning. I. An evaluation of cereal pastures as related to tetany in beef cows.

Forage samples were obtained from three wheat and rye mixed pastures (replications) from December 1979, to April 1980 (140 d), while they were being grazed by mature cows at the Southwestern Livestock and Forage Research Station, El Reno, Oklahoma. These samples were taken three times during December, twice monthly in January and February and weekly in March and April. Samples were analyzed for dry matter, ash, N, K, Ca, Mg, P, ash alkalinity, aconitic, malic and citric acids, total lipids, NO3-N, Na and total nonstructural carbohydrates (TNC). In vitro digestibility was also determined. The N:TNC ratio, estimated plasma Mg levels and K:(Ca + Mg) ratio (tetany ratio) were calculated. On d 105 (March 19), 16% (five of 32 head) of the cows developed tetany. At tetany, the forage K, protein, digestibility, ash alkalinity, aconitic acid and total lipids increased suddenly and markedly. Forage dry matter, TNC and ash decreased. Forage Ca and Mg were slightly below or equal to the animals' requirements and remained relatively constant during the period of tetany. Forage P increased about 2 wk before tetany and decreased after tetany occurred. The levels of forage NO3-N and Na did not appear to be related to the incidence of tetany. The N:TNC ratios exceeded .4 immediately before tetany and two sampling periods thereafter. The estimated plasma Mg levels were lowest at tetany and shortly thereafter and tetany ratio exceeded 2.2 during most of the study, with peaks of 3.2 in December, at tetany and in early April.

Animals↗
PubMed1999

Postoperative tetany in Graves disease: important role of vitamin D metabolites.

OBJECTIVE: To test the authors' hypothesis of the causal mechanism(s) of postoperative tetany in patients with Graves disease. SUMMARY BACKGROUND DATA: Previous studies by the authors suggested that postoperative tetany in patients with Graves disease occurs during the period of bone restoration and resulted from continuation of a calcium flux into bone concomitant with transient hypoparathyroidism induced by surgery. PATIENTS AND METHODS: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)2D), and bone metabolic markers in 109 consecutive patients with Graves disease who underwent subtotal thyroidectomy. RESULTS: Preoperative serum iPTH levels negatively correlated with ionized calcium levels and positively correlated with 1,25(OH)2D or 1,25(OH)2D/25OHD. After the operation, there was a significant decline in levels of ionized calcium, magnesium, and iPTH. Serum iPTH was not detected in 15 patients after surgery. Four of these 15 patients, and 1 patient whose iPTH level was below normal, developed tetany. Preoperative serum ionized calcium levels were significantly lower, and iPTH levels were higher, in the 5 patients with tetany than in the 11 patients who did not develop tetany despite undetectable iPTH levels. The tetany group had significantly lower serum 25OHD levels and higher 1,25(OH)2D levels, and had increased 1,25(OH)2D/25OHD as an index of the renal 25OHD-1-hydroxylase activity than those in the nontetany group. These results suggest that patients with a high serum level of iPTH as a result of low serum calcium levels (secondary hyperparathyroidism) are susceptible to tetany under conditions of hypoparathyroid function after surgery. CONCLUSIONS: Postoperative tetany occurs in patients with secondary hyperparathyroidism caused by a relative deficiency in calcium and vitamin D because of their increased demand for bone restoration after preoperative medical therapy concomitant with transient hypoparathyroidism after surgery. Calcium and vitamin D supplements may be recommended before and/or after surgery for patients in whom postoperative tetany is expected to develop.

Adolescent↗
PubMed2005

Intraoperative parathyroid hormone assay in patients with Graves' disease for prediction of postoperative tetany.

We measured intraoperative parathyroid hormone (IOPTH) levels before and after thyroidectomy in a large group of patients to test whether changes in IOPTH can predict postoperative tetany. Subjects were 111 consecutive patients (94 females and 17 males) with Graves' disease undergoing subtotal thyroidectomy. Blood samples for IOPTH assay were obtained after anesthesia (basal) and following skin closure (postoperative). Data were compared between patients who developed tetany (n = 9) and those who did not (n = 102). There was no significant difference in sex, age, period of antithyroid drug administration, or the weight of the thyroid between the two groups. The preoperative serum calcium level was significantly lower (p < 0.05) and the basal IOPTH significantly higher (p < 0.05) in the tetany group than in the non-tetany group. The IOPTH level was significantly lower (p < 0.005) and the average percent decrease in IOPTH levels was higher (p < 0.001) in the tetany group than in the non-tetany group. A decrease in IOPTH of more than 70% was shown to be 78% sensitive, 94% specific, and 93% accurate, and it has 78% positive predictive value and 94% negative predictive value for the development of tetany. Our study shows that a postoperative decrease of IOPTH level is the most predictive of postoperative tetany of the clinical risk factors investigated. We recommend IOPTH measurement as an adjunct to postoperative management of patients with Graves' disease to assist in preventing hypocalcemia and determining the earliest time for safe discharge.

Adolescent↗
PubMed1975

Tetany: quantitative interrelationships between calcium and alkalosis.

Tetany occurs with hypocalcemia and alkalosis or both. The interrelationship of calcium and acid-base balance necessary for inducing tetany, the role of the central nervous system, and the rate of development of hypocalcemia have been investigated. Tetany occurred in less than 50 percent of one group of dogs made alkalotic by hyperventilation or made hypocalcemic by infusion of ethylene glycol-bis(beta-amino ethyl ether) N, N'-tetraacetate. In contrast, hypocalcemia combined with hypocapnic alkalosis always produced tetany. Slowly evolving hypocalcemia was achieved inanother group of dogs by thyroparathyroidectomy, and tetany was induced postoperatively by hypocapnic alkalosis. An identical relationship between serum calcium ion concentration and arterial pH or CO2 tension was found in both groups. Tetany could not be related to the cerebrospinal fluid (CSF) calcium ion content in either group. Hypocalcemia and alkalosis are therefore coparticipants in the development of tetany and are independent of the rate of development of hypocalcemia and of CSF calcium ion concentration. The importance of alkalosis in tetany with hypoparathyroidism is emphasized.

Alkalosis, Respiratory↗
PubMed2000

Seasonal changes in calcium homeostasis affect the incidence of postoperative tetany in patients with Graves' disease.

BACKGROUND: We have found that postoperative tetany occurs in patients with Graves' disease who have secondary hyperparathyroidism caused by a deficiency in calcium and vitamin D concomitant with transient hypoparathyroidism after surgery. There are seasonal variations in serum 25-hydroxyvitamin D (25[OH]D) concentrations. The purpose of this study was to investigate the effects of seasonal changes in calcium homeostasis on the incidence of postoperative tetany in patients with Graves' disease who undergo subtotal thyroidectomy. PATIENTS AND METHODS: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25(OH)D, and 1,25-dihydroxyvitamin D (1,25[OH]2D) in female patients with Graves' disease who underwent subtotal thyroidectomy during the summer (n = 89) and during the winter (n = 89). RESULTS: The serum levels of calcium, magnesium, and 25(OH)D were significantly higher, but iPTH levels and 1,25(OH)2D levels were lower in summer than in winter. The percentage of vitamin D deficiency (25(OH)D < 25 nmol/L) was 23% in summer and 62% in winter (P < .001). iPTH was below the detection limit on the first postoperative day in 15 patients (13.8%) in summer and in 13 patients (11.4%) in winter. In summery, tetany developed in only 4 of 15 patients and in one patient whose iPTH level was below normal (incidence of tetany, 5.6%). In winter, however, tetany developed in 6 of 13 patients and in 4 patients whose iPTH level was below normal (incidence of tetany, 11.2%). CONCLUSIONS: Patients with Graves' disease are more susceptible to calcium and vitamin D deficiency during the winter than during the summer, resulting in the tendency toward a higher incidence of postoperative tetany in winter.

Adult↗