Objective: This study aims to estimate the prevalence of and determine physician approaches to the screening and management of lithium-associated thyroid and parathyroid disorders in British Columbia, Canada.
Methods: Serum lithium and thyroid/parathyroid laboratory data were collected retrospectively for patients with lithium levels measured at seven BC hospitals between 2012 and 2021. A mail-out survey about screening and management of thyroid/parathyroid disorders in patients on lithium was sent to the ordering physicians of patients with abnormal results. Three months after, a follow-up questionnaire was sent to respondents, and the original survey was re-sent to non-responders.
Results: Of 4917 patients, 1.9 % had PTH (mean 22.33 ± 23.00 pmol/L) and 77.1 % had TSH (mean 3.61 ± 6.69 pmol/L) measured. Of 222 hypercalcemic patients (defined as any serum calcium or ionized calcium above the laboratory reference), 17.6 % had a PTH level measured. From 294 surveys sent to 214 physicians, the overall response rate was 31.6 % (n = 93) with twelve fully completed surveys. All twelve respondents monitored TSH levels every 6-12 months, and eight physicians monitored PTH and/or calcium at variable intervals. Two physicians routinely ordered both thyroid and parathyroid screening laboratory tests. Of the 80 non-respondents, limited patient contact was the most common reason for opting out (n = 27).
Conclusions: Our results suggest biochemical screening for lithium-associated parathyroid disorders is less common than for thyroid disorders. There is insufficient data to determine the true prevalence of lithium-associated thyroid and parathyroid disorders. This highlights the need for updated clinical guidelines for management of lithium-associated thyroid and parathyroid disorders.
Keywords: Hyperparathyroidism; Hyperthyroidism; Hypothyroidism; Lithium; Parathyroid; Thyroid.
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