It is the marked increase in calcium levels (greater than 13-14 mg / dl) with concomitant dehydration.
Occasionally, a patient with primary hyperparathyroidism (or pseudohyperparathyroidism) - already known or not - presents with a hypercalcemic crisis. It is more common in older people, especially if they are immobilized by some intercurrent condition.
The kidney's difficulty in concentrating urine in the presence of hypercalcemia has already been mentioned in the chapter on hyperparathyroidism, with the consequent polyuria that can lead to marked dehydration and a decrease in the glomerular filtration rate. This is even more the case in clouded or comatose subjects who cannot replace fluids by mouth, and in whom parenteral fluid replacement is absent or insufficient.
Symptoms and signs
The clinical signs are those of a depressed sensorium, with varying degrees of coma; the tendon reflexes are depressed or absent, but there are no focal neurologic signs. Furthermore, dehydration is evident. There may be severe abdominal pain, nausea, and vomiting. Calcemia is usually very high (> 15 mg / dl).
Calcemia should be systematically requested in all patients who are in bed for long periods, especially if they are drowsy; in all patients in a coma of unknown origin; and in every patient with a malignant neoplasm.
Regarding the investigation of the cause of the syndrome, it is appropriate to refer to the guidelines outlined in the chapter on hyperparathyroidism. When the cause of the hypercalcemic crisis is primary hyperparathyroidism, serum PTH levels are extremely high (reaching 20 times the top of the normal range).