Hypercalcaemia and Hypercalciuria

Hypercalcaemia (too much calcium in the blood) and Hypercalciuria (too much calcium in urine) can occur in a small, but significant number of patients with sarcoidosis. The abnormal calcium metabolism is most likely associated with increased activity of the body’s enzyme (1-alpha hydroxylase) in sarcoidosis patients which is responsible for the production of calcitriol (active form of vitamin D). 

Hypercalcaemia

Hypercalcaemia has been reported in 5-10% of sarcoidosis patients. It is caused due to increased enzyme (1-alpha hydrolase) in sarcoidosis patients which converts all forms of vitamin D (sun exposure, diet, supplements) to its active form. Hypercalcemia negatively impacts the body’s ability to carry out its normal functions, which in some cases can be life-threatening.   Hypercalcemia is associated with kidney dysfunction and even failure in up to half of patients with hypercalcemia.

Once a sarcoidosis patient is found to have hypercalcemia in regular blood tests (either when investigating symptoms or incidentally) he would need to check vitamin D levels, PTH levels, 24-hour urine calcium levels as well as renal function (urine, creatinine, electrolytes). Primary hyperparathyroidism needs to be excluded. Sun exposure and vitamin D supplementation may often result in hypercalcemia. The severity depends on many factors, but hypercalcemia in sarcoidosis responds well to treatment.

Hypercalciuria

Hypercalciuria is far more common than Hypercalcaemia – between 30-40% of sarcoidosis patients suffer from excess levels of calcium in the urine. Excess calcium in the urine causes problems because it tends to form salts that crystallize – these crystals can cause pain or other urinary symptoms, depending upon their size and location, with large crystals being commonly known as kidney stones.

Treatment of hypercalcaemia and hypercalciuria

Hypercalcemia related to sarcoidosis is a well-described target of sarcoidosis specific treatments. Steroids in the first instance are used along with non-sarcoidosis type of management including hydration (e.g. intravenous fluids) and sometimes diuretics. Depending on the level of calcium levels in the blood patients may need hospitalization for intravenous fluids. Consistent monitoring of calcium levels is essential to ensure the condition does not worsen and to eliminate the risk of medications causing any additional side effects.

If mild, hypercalciuria can be managed with dietary change and vitamin D supplements cessation. Limiting time spent in the sun may also be considered. If these treatments fail, hypercalciuria would indicate systemic sarcoidosis activity and treatment with steroids and other medications may be considered.