Lithium therapy as cause for hypercalcemia and hyperparathyroidism

Introduction: Hypercalcemia presents quite often during diagnostic procedures for osteoporosis. Beside malignancy or primary hyperparathyreoidism, there are several rare reasons including lithium therapy.

Methods: In 2006, a woman (58yr) presented with skeletal pain. Medical history showed Grave's disease and hyperthyroidism as well as lithium therapy for a bipolar psychotic disorder. Diagnostic workup was done using routine laboratory assessments (hormones, clinical chemistry), diagnostic imaging, bone histology.

Results: We found hypercalcemia (calcium 2.8 mM), normal PTH (23 ng/ml), all other laboratory parameters were normal. The thyroid gland was small with low echo density. Bone densitometry showed osteopenia (T-value -1.7). No neurologic disease or fractures were detected..

Szintigraphy yielded higher signals at the skull, MRI of skull was normal. Bone marrow histology showed mild osteomalacia and osteitis fibrosa (as seen in hyperparathyreoidism), but no hematological disease.

Therapy with ibandronate 3 mg every 3 month was started. After 6 months, the patient presented herself again with resumed lithium therapy. Calcium levels continued to be slightly elevated with 2.63 mM, but now PTH was also slightly raised with 64 pg/ml.

Ibandronate therapy resulted in reduced skeletal pain. Vitamin D supplementation with 500 IU daily was added. Under this regimen calcium levels were between 2.5 and 2.7 mM. Bone density increased by 3%.

In July 2008 serum calcium levels increased to 2.9 mM, PTH now 99 pg/ml.

In April 2012 ultrasound sonography revealed a parathyroid adenoma for the first time, confirmed by sestamibi-szintigraphy. Calcium in July 2012 was 2.9 mM, and PTH 81 ng/l. Surgery of the neck was performed in November 2012, confirming the parathyroid adenoma. Serum levels of calcium and PTH normalized after surgery.

Conclusion: The case presented here demonstrates the development of a new parathyroid adenoma under lithium therapy.