Thyroid hormones modulate uric acid metabolism in patients with recent onset subclinical hypothyroidism by improving insulin sensitivity.

Some evidence suggests a relationship between thyroid dysfunction and uric acid (UA) metabolism, but the potential influential role of thyroid hormones on UA metabolism is still debated. This report was designed to evaluate the influential role of levothyroxine (L-T4) replacement therapy on circulating levels of UA in patients with recent onset post-thyroidectomy subclinical hypothyroidism. Circulating levels of thyroid hormones, UA and other metabolic parameters were assessed in 155 recently thyroidectomized patients (131 females, mean age 51.1 ± 12.7 years) at baseline (5-7 day after surgery) and after 2 months under replacement therapy with L-T4. At baseline, circulating levels of thyroid hormones were indicative of a subclinical hypothyroidism (TSH 8.2 ± 5.1 mU/mL, FT3 2.1 ± 0.7 pg/mL, FT4 9.2 ± 3.4 pg/mL). The mean serum UA concentration was 5.0 ± 1.3 mg/dL, while the prevalence of hyperuricemia, defined by serum UA levels > 6 mg/dL, was 22.6%. Serum UA levels at baseline were significantly correlated with HOMA-IR index (r = 0.475, p < 0.0001). After 2 months under the replacement therapy with L-T4, both serum UA levels (- 1.2 ± 0.9 mg/dL, p < 0.0001 vs. baseline) and HOMA-IR (- 0.3 ± 1.5 mmol/L, p = 0.0328 vs. baseline) significantly decreased. Multivariate regression analysis revealed that changes in HOMA-IR explained 23% of the variations of serum UA levels under L-T4 replacement therapy (ß = 0.295, p < 0.0001, R2 = 0.230). Our study suggests that thyroid hormones could modulate UA metabolism in patients with recent onset subclinical hypothyroidism likely by improving insulin sensitivity.

Early prediction of postthyroidectomy hypocalcemia by one single iPTH measurement.

BACKGROUND: We prospectively evaluated the possibility to make an early prediction of postthyroidectomy hypocalcemia by postoperative intact parathyroid hormone (iPTH) measurements. METHODS: Fifty-three consecutive patients who underwent bilateral thyroid resection were included; iPTH was measured preoperatively, at the end of the surgical procedure, and at 2, 4, 6, 24, and 48 hours after the operation. Patients who had hypocalcemia (serum total calcium, <8.0 mg/dL) were compared with normocalcemic patients. RESULTS: Sixteen patients experienced hypocalcemia. Six patients experienced symptoms. No significant difference was found between hypocalcemic and normocalcemic patients concerning demographic, pathologic, and preoperative laboratory data, surgical procedure, and intraoperative findings. Postoperative iPTH levels were reduced in hypocalcemic patients at the end of the procedure and at 2, 4, 6, 24, and 48 hours after the operation ( P < .001). IPTH levels below the normal range (<10 pg/mL) at 4 and 6 hours after the operation correctly predicted postoperative hypocalcemia and symptoms in all but 1 patient with a self-limiting, asymptomatic hypocalcemia (serum calcium concentration, 7.8 mg/dL) (specificity, 100%; sensitivity, 94%; overall accuracy, 98%). CONCLUSIONS: One single iPTH measurement reliably can predict, early after thyroidectomy, which patients are prone to clinically relevant postoperative hypocalcemia and necessitate supplementation treatment and which patients are eligible for a safe early discharge.