Hypercalcemia

Generality

Hypercalcemia is a clinical condition characterized by an excess of calcium in the blood (concentrations above 10.5 mg / dL in adults).

In the article dedicated to calcemia, we saw how the blood levels of the mineral depend on the activity of vitamin D and two hormones, parathyroid hormone and calcitonin, which in turn modulate the deposit / release of calcium from the bones, as well as its renal reabsorption / excretion e

the degree of absorption at the enteric level. It follows that hypercalcemia can be caused by three different mechanisms, which can come into play in isolation or in combination:

excessive release, localized or generalized, of calcium from the bones (for example due to increased secretion of parathyroid, as happens in hyperparathyroidism, the most common cause of hypercalcemia);
increased intestinal absorption of calcium (for example from excessive vitamin D intake);
decreased excretion of calcium in the kidney (as occurs in renal insufficiency).

Symptoms

Depiction of a parathyroid adenoma, a benign tumor of a parathyroid gland, almost always responsible for hyperparathyroidism with consequent hypercalcemia. From https://en.wikipedia.org

Due to the numerous and important functions performed by calcium in the body, hypercalcemia can be accompanied by a constellation of signs and symptoms of varying entities in relation to the degree of abnormality and the general health conditions of the patient. These include constipation, nausea, gastric hyperacidity (hypercalcemia increases gastrin secretion), abdominal pain, vomiting, psychological disorders (depression, confusion, apathy, lethargy up to coma), weakness, thirst, polyuria, dehydration and pain While in patients with modest hypercalcemia (11-12 mg / dL) the condition may be asymptomatic, in severe forms hypercalcemia is accompanied by quite severe symptoms, to the point of constituting a real medical emergency (severe arrhythmias, coma, kidney failure).

Causes and associated diseases

Infections, inflammatory processes, hyperparathyroidism (increased function of the parathyroid glands, usually due to benign tumors, with increased blood levels of parathyroid hormone), tumors with bone metastases (typical is the case of breast and lung cancer), tumors that release parathyroid hormone-like substances (paraneoplastic syndrome), Paget's disease, hyperthyroidism (increased thyroid function), bone fractures combined with prolonged immobilization, high-protein diet, excessive vitamin D intake, vitamin A intoxication, kidney transplant, tuberculosis , sarcoidosis, multiple myeloma, leukemia, trauma, stress and kidney failure.

Some iatrogenic causes include some diuretics (thiazides), thyroid hormone overdose (Eutirox), tamoxifen, and lithium therapy (mainly used in the treatment of bipolar disorder).

Treatment

See also: Medicines for the treatment of hypercalcemia

To establish an adequate treatment of hypercalcemia it is first of all necessary to determine the cause of origin (in this regard the diagram shown in the figure may be useful, clicking on it to enlarge it).

Emergency hospital therapy must meet three distinct criteria: hydration, increased salt intake and forced diuresis. The patient's rehydration using saline solutions (renal excretion of sodium facilitates that of calcium), must therefore be subsequently accompanied by treatment diuretic (furosemide) to avoid an excessive increase in blood volume (resulting in hypertension and risk of pulmonary edema). Two other important drugs used in the treatment of hypercalcemia are bisphosphonates and calcitonin (analogue of the natural hormone, capable of inhibiting bone resorption and increasing the elimination of calcium in the urine). Bisphosphonates are drugs analogous to pyrophosphate with high affinity for bone. Stable and resistant to phosphatases, they have the characteristic of inhibiting the activity of osteoclasts, the cells responsible for bone resorption; these drugs must be used with particular caution in the presence of hypercalcemia with renal insufficiency, for which it may be necessary to resort to dialysis .