A Case of Lithium-Associated Hypocalciuric Hypercalcemia

Area of Science:

• Nephrology
• Endocrinology
• Psychiatry

Background:

• Lithium is a primary treatment for bipolar disorder, used for acute episodes and long-term prophylaxis.
• Lithium therapy is associated with hypercalcemia in a notable subset of patients.
• Hypercalcemia is frequently attributed to lithium-induced hyperparathyroidism, often involving parathyroid adenoma or hyperplasia.

Observation:

• A 67-year-old woman on long-term lithium therapy for bipolar disease presented with lethargy and cognitive difficulties.
• Investigations revealed elevated serum calcium and paradoxically low urinary calcium excretion, indicative of hypocalciuric hypercalcemia.
• The patient had no other identifiable cause for these biochemical abnormalities and no family history of familial hypocalciuric hypercalcemia.

Findings:

• Neck imaging excluded parathyroid adenoma or hyperplasia as the cause of hypercalcemia.
• The clinical presentation and diagnostic workup were consistent with lithium-associated hypocalciuric hypercalcemia.
• This diagnosis was established despite the absence of typical parathyroid pathology.

Implications:

• This case underscores the importance of considering lithium-associated hypocalciuric hypercalcemia, even in the absence of parathyroid adenoma or hyperplasia.
• It highlights a distinct mechanism of lithium-induced hypercalcemia that requires careful diagnosis and management.
• Continued surveillance is crucial for patients with lithium-associated hypocalciuric hypercalcemia to monitor their clinical status.