Predictive risk factors for postoperative tetany in female patients with Graves' disease.
BACKGROUND
Postoperative tetany occurs in patients with secondary hyperparathyroidism caused by a deficiency in calcium and vitamin D concomitant with transient hypoparathyroidism induced by surgery. In the present study, we further clarified the risk factors by referring to serum 25-hydroxyvitamin D [25(OH)D] and alkaline phosphatase.


METHODS
The serum levels of intact parathyroid hormone, calcium and other electrolytes, and 25-hydroxyvitamin D [25(OH)D] were measured preoperatively in 178 female patients with Graves' disease who underwent subtotal thyroidectomy.


RESULTS
Of the 178 female patients, 15 (8.4%) developed tetany. Univariate analysis of 16 possible risk factors showed that 2 were statistically significant: serum 25(OH)D and alkaline phosphatase levels. The incidence of tetany according to the serum levels of 25(OH)D and alkaline phosphatase was 19.1% (9/47) in patients with 25(OH)D < or = 25 nmol/L and alkaline phosphatase > 155, 11.8% (4/34) in those with 25(OH)D < or = 25 nmol/L and alkaline phosphatase < or = 155, 6.7% (2/30) in those with 25(OH)D > 25 nmol/L and alkaline phosphatase > 155, and 0% (0/50) in those with 25(OH)D > 25 nmol/L and alkaline phosphatase < or = 155.


CONCLUSIONS
Patients with Graves' disease who have vitamin D deficiency with high serum alkaline phosphatase levels are the highest-risk group for postoperative tetany. Serum 25(OH)D and alkaline phosphatase should be monitored in patients with Graves' disease.
Yamashita
H
H
Noguchi Thyroid Clinic and Hospital Foundation, Beppu, Oita, Japan.
Noguchi
S
S
Murakami
T
T
Uchino
S
S
Watanabe
S
S
Ohshima
A
A
Toda
M
M
Yamashita
H
H
Kawamoto
H
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D000704:Analysis of Variance; D002118:Calcium / Q000097:blood / Q000172:deficiency; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006111:Graves Disease / Q000601:surgery*; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000209:etiology*; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011237:Predictive Value of Tests; D012307:Risk Factors; D012727:Sex Characteristics; D017678:Sex Distribution; D013746:Tetany / Q000097:blood / Q000209:etiology*; D013965:Thyroidectomy / Q000009:adverse effects* / Q000379:methods; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium