Abstract
Background: Lithium, commonly used to treat various psychiatric disorders such as bipolar disorder, can cause acute toxicity that presents with nausea, vomiting and diarrhea. Lithium can also cause life-threatening endocrine abnormalities, including hypercalcemia, hypernatremia, and both hypo- and hyperthyroidism.
Clinical Case: A 61-year old female with hypothyroidism, bipolar disorder, hyperparathyroidism with two-gland parathyroidectomy on lithium for over 30 years presented with altered mental status.
Initial labs revealed elevated creatinine 1.92 mg/dL (0.8-2.00mg/dL) compared to baseline 0.82 mg/dL, sodium 154 mg/dL (135-147 mg/dL), Corrected calcium 11.7 mg/dL (8.5-10.5 mg/dL), PTH 96 pg/mL (15-65 pg/mL), and high lithium levels 1.45 mmol/L (0.60-1.20 mmol/L). Further studies showed hypotonic polyuria with no increase in urine osmolality after desmopressin, consistent with nephrogenic diabetes insipidus. Lithium was held and she was treated with aggressive intravenous hydration with dextrose 5% water.
Hypercalcemia is thought to result from increased secretion of PTH due to an increased set point at which calcium suppresses PTH release; this often resolves once lithium is stopped. Lithium can also unmask previously unrecognized mild hyperparathyroidism, and/or raise serum PTH concentrations independent of calcium levels.1 The drug interferes with the kidneys’ ability to concentrate urine in the collecting tubules by desensitizing response to antidiuretic hormone, causing diabetes insipidus. The resulting volume depletion from excessive urinary water loss in turn lead to acute kidney injury and hypernatremia.2 Hypothyroidism results from lithium-inhibited synthesis and release of thyroid hormones and decreases iodine trapping.
Conclusion: Although these are infrequent complications of lithium use, they remain pertinent clinical findings to consider due to their morbidity. In this case, our patient may have avoided multiple chronic electrolyte abnormalities leading to altered mental status if lithium toxicity had been recognized earlier.
References:1. García-Maldonado, Gerardo, and Rubén de Jesús Castro-García. “Endocrinological Disorders Related To The Medical Use Of Lithium. A Narrative Review”. Revista Colombiana De Psiquiatría (English Ed.), vol 48, no. 1, 2019, pp. 35-43. Elsevier BV, doi:10.1016/j.rcpeng.2018.12.005.
2. Tasci, E. “Lithium-Induced Nephrogenic Diabetes Insipidus Responsive To Desmopressin”. Acta Endocrinologica (Bucharest), vol 15, no. 2, 2019, pp. 270-271. ACTA Endocrinologica Foundation, doi:10.4183/aeb.2019.270.
Lithium, an old friend and a forgotten enemy
