Lithium-associated primary hyperparathyroidism:: An evaluation of screening and referral patterns in a southeastern veteran population.

BACKGROUND: Long-term lithium therapy has a well-established but under-recognized association with primary hyperparathyroidism. Rates of hypercalcemia, screening for primary hyperparathyroidism, and referral for parathyroidectomy were evaluated among United States veterans on long-term lithium therapy. METHODS: Patients undergoing chronic long-term lithium therapy (>12 months) were identified from 1999 to 2022. Demographics, long-term lithium therapy duration, post-treatment calcium, parathyroid hormone, creatinine, and vitamin D levels were abstracted. Rates of screening for hypercalcemia (calcium ≥10.2 mg/dL), primary hyperparathyroidism (parathyroid hormone ≥30 pg/mL in the setting of hypercalcemia), referral for parathyroidectomy, and outcomes were evaluated. RESULTS: A total of 1,356 patients underwent long-term lithium therapy, 514 of whom received chronic long-term lithium therapy. Baseline characteristics of patients with and without post-treatment hypercalcemia were compared. Of 148 patients with post-treatment hypercalcemia, 112 (74.7%) underwent no further evaluation for primary hyperparathyroidism, while 36 (25.3%) patients had a parathyroid hormone level recorded. Although 33 (91.7%) hypercalcemic patients screened positive for primary hyperparathyroidism, only 5 (13%) were referred for parathyroidectomy. Of the 4 patients who underwent parathyroidectomy, mean calcium was 11.2 mg/dL (range 11.1-11.4), and mean parathyroid hormone was 272 pg/mL (range 108-622). Three patients were localized on preoperative imaging, 2 of whom underwent unilateral exploration with cure, with 1 experiencing recurrence at 31 months. The remaining patient who localized preoperatively underwent bilateral exploration and had 2 ipsilateral glands resected and persistence. The patient who did not localize preoperatively underwent bilateral exploration with 3 gland resection and cure. CONCLUSIONS: Screening for primary hyperparathyroidism and referral for parathyroidectomy are underutilized in United States veterans undergoing chronic long-term lithium therapy. Institutional protocols to standardize screening, surveillance, and referrals to endocrinology/endocrine surgery could benefit this population at increased risk for primary hyperparathyroidism.

Acute Kidney Injury Following Methimazole Initiation: A Case Report.

OBJECTIVE: Nephritis has been rarely associated with methimazole, primarily in the development of nephrotic syndrome. We describe a case of acute kidney injury without evidence of nephrotic syndrome following methimazole initiation. METHODS: We present the relevant history, laboratory data, and nuclear medicine data and review relevant documentation from the literature. RESULTS: A 72-year-old male recently diagnosed with new-onset atrial fibrillation was found to have suppressed thyroid-stimulating hormone (TSH) levels; elevated free T3, T4, and thyroid-stimulating immunoglobulin (TSI) levels; and a nonnodular thyroid gland with normal iodine uptake. He was diagnosed with Graves' disease and treated with propylthiouracil (PTU) for 5 years. When his poor compliance with PTU was impeding his antithyroid treatment, he was converted to methimazole. Within 1 month following methimazole initiation, his serum creatinine (SCr) had risen to 1.6× baseline in the absence of other contributing nephrotoxins. SCr returned to baseline within 2 weeks of methimazole discontinuation, and the patient was subsequently managed on PTU. CONCLUSION: Acute kidney injury with or without the presence of nephrotic syndrome may occur during treatment with methimazole. Renal function should be closely monitored after the initiation of methimazole to prevent progressive renal dysfunction.