Secondary hypoparathyroidism after DTC effects on bone metabolism and health management

Abstract

Objective To investigate the effects of secondary hypoparathyroidism on bone metabolism and health management in patients with differentiated thyroid carcinoma(DTC). Methods Sixty patients with DTC who underwent total or subtotal thyroidectomy from January 2017 to May 2018 were enrolled. Among them, 30 patients had secondary hypoparathyroidism and hypocalcemia(hypothyroidism), while the other 30 patients had normal parathyroid function(control group). These two groups of patients were routinely examined for their parathyroid hormone(PTH), vitamin D, serum calcium, serum phosphorus, alkaline phosphatase(ALP), free triiodothyronine(FT3), free thyroxine(FT4), and thyroid stimulating hormone(TSH) at 1, 6, and 12 months after surgery and to determine dual-energy X-ray bone mineral density(BMD) and health-management-related indicators. PTH, vitamin D, serum calcium, serum phosphorus, and ALP in the parathyroid group were tested by conducting a paired t-test, and the indicators for the parathyroid and control groups(FT3, FT4, TSH, and L2 to L4, neck of femoral, femur trochanter, Ward’ s triangle BMD value) were compared by conducting an independent sample t-test. Results 1. A statistically significant difference in PTH, serum calcium, and serum phosphorus was observed among patients with hypothyroidism at 1 and 6 months after surgery, 6 months after surgery, and 12 months after surgery(PTH: t= –2.467, –2.753, P=0.021, 0.033; serum calcium: t=–2.941, –3.652, P=0.007, 0.002; serum phosphorus: t=4.550, 4.167, P=0.000, 0.004), but no significant difference was observed in terms of vitamin D and ALP(vitamin D: t=2.153, 1.965, P=0.062, 0.074; ALP: t=1.970, 1.672, P=0.061, 0.066); 2. At 12 months after surgery, the BMD of the neck of femoral decreased in the parathyroid group, showing a statistically significant difference from the control group(t=1.08, P=0.002). At 1, 6, and 12 months after surgery, the patients with hypothyroidism showed no significant differences from the control group in terms of thyroid function level(FT3, FT4, and TSH), lumbar vertebrae(L2 to L4), Ward’s triangle, and femur trochanter BMD(t=0.606 to 1.82, all P>0.05). 3. After taking calcium and vitamin D, the clinical symptoms of hypocalcemia in patients with hypothyroidism were significantly improved. Twelve months after surgery, hand and foot numbness and muscle spasms accounted for 6.67% of the symptoms, and after taking calcium and vitamin D, the medication compliance of the patients decreased to 80%. Conclusions 1.The BMD of neck of femoral in patients with hypothyroidism decreased at 12 months after surgery, and the BMD of lumbar vertebrae(L2~L4), Ward’s triangle and femur trochanter was not significant; 2.Most patients with parathyroid hypofunction showed clinical manifestations of hypocalcemia after DTC, and their symptoms were significantly relieved after the calcium and active vitamin D treatment. However, the medication compliance of these patients gradually declined. Therefore, health education and management should be further strengthened. Key words: Differentiated thyroid carcinoma; Hypoparathyroidism; Bone density; Health management