Calcium-alkali syndrome in post-surgical hypoparathyroidism

Severe Hypercalcemia Caused by Calcium-Alkali Syndrome after 15 Years of Postoperative Hypoparathyroidism in a Patient with Undiagnosed Hyperaldosteronism

Introduction

The triad of hypercalcemia, metabolic alkalosis, and acute kidney injury associated with ingesting high doses of calcium and absorbable bases characterizes the calcium-alkali syndrome. Clinical Case. We report the case of a patient with postthyroidectomy hypoparathyroidism 15 years ago due to differentiated thyroid cancer who presented with severe hypercalcemia. He had adequate control of calcemia for many years on treatment with calcitriol and calcium carbonate and hypertension treated with amlodipine, losartan, and hydrochlorothiazide. After a period of loss to follow-up, he suddenly presents with severe hypercalcemia, metabolic alkalosis, and loss of renal function. Upon hydration and withdrawal of calcitriol and calcium replacements, hypercalcemia resolved. The etiological investigation identified no granulomatous or neoplastic diseases, but an aldosterone-producing adrenal incidentaloma was found. The cause of hypercalcemia in this patient was calcium-alkali syndrome due to calcium carbonate replacement potentiated by hydrochlorothiazide and primary aldosteronism. Six months after the hospitalization and suspension of calcium and vitamin D, the patient returned to hypocalcemia, reinforcing the diagnosis.

Conclusion

Although seldom described, the calcium-alkali syndrome is an expected complication for individuals with postoperative hypoparathyroidism, as they require lifelong calcium and vitamin D supplementation. This case also shows the importance of hydrochlorothiazide use and primary aldosteronism as possible triggers of life-threatening hypercalcemia.

A Case of Hypercalcemia after Thyroidectomy

Total thyroidectomy is complicated by hypoparathyroidism in 1-3% of patients. Hypoparathyroidism is treated with oral calcium and vitamin-D supplements. Everyday use of calcium and vitamin D can lead sometimes to hypercalcemia. Ingestion of large amounts of calcium and absorbable alkali that cause hypercalcemia, various degrees of renal failure, and metabolic alkalosis, can be associated with a diagnosis of calcium-alkali syndrome. This syndrome was first identified as milkalkali syndrome, after treatment of peptic ulcer disease with milk and alkali which was widely adopted at the beginning of the 20th century. With the introduction of histamine-2 blockers and proton pump inhibitors, the occurrence of milk-alkali syndrome became rare; however, it has emerged recently as calcium-alkali syndrome because of the wide availability and increasing use of calcium carbonate, mostly for osteoporosis prevention. We present a female patient with hypoparathyroidism who presented with hypercalcemia and alkalosis as a result of treatment with calcium carbonate, vitamin D and thiazide diuretic. The patient was treated successfully by discontinuation of the above drugs, intravenous fluid administration and enhancement of calcium renal excretion. Hypercalcemia presenting as calcium-alkali syndrome is a diagnosis that requires a high index of suspicion in order to quickly identify the disorder and initiate appropriate therapy. It is important for clinicians to keep the syndrome on their list of differential diagnosis.