What is hypocalcemia and its causes?

Hypocalcemia is a disease in which the levels of calcium in the blood are too low. It produces neuromuscular and neuropsychiatric symptoms, which can become serious if left untreated.

We speak of hypocalcemia when calcium levels in the blood are low. Calcium is an essential substance for the contraction of muscles, the transmission of nerve impulses, the activation of blood clotting systems, and bones’ formation. Therefore, hypocalcemia will produce symptoms at the muscular, nervous, and bone levels fundamentally.

Some signs and symptoms that may suggest low blood calcium include tingling in the mouth, hands, feet, muscle aches and spasms, shortness of breath, palpitations, dry skin, disorientation, etc. delusions, and hallucinations.

It is a problem that can affect all types of people, from children to the elderly. However, it is especially common in certain population groups such as the elderly, pregnant women, postmenopausal women, and prolonged treatment with corticosteroids or vegetarians. Those patients who have undergone surgery of the thyroid or parathyroid gland have a significant risk of developing hypocalcemia.

The causes of hypocalcemia vary, from a low intake of calcium in our usual diet to an increase in this mineral’s losses due to the consumption of drugs such as diuretics. Alterations in the parathyroid gland, responsible for producing parathyroid hormone or PTH (whose function is to regulate calcium and phosphorus metabolism ), is another very common cause of hypocalcemia.

This disorder diagnosis is carried out using a blood test, performing other diagnostic tests if the specialist considers it appropriate. Hypocalcemia is considered when the amount of ionic calcium is less than 4.75 mg/dl or when the amount of total calcium in the blood is below 8.5 mg/dl.

If hypocalcemia is very severe – when levels are very low or fall rapidly – urgent intravenous treatment may be necessary, as the patient’s life may be in danger. However, most of the time, calcium levels can be replenished through dietary measures or by taking calcium and vitamin D supplements.

A balanced diet, which includes dairy products, fish such as salmon, and green leafy vegetables such as spinach, is essential to avoid this problem.

Causes of hypocalcemia

The causes of hypocalcemia are many and varied. In summary, it could be said that blood calcium may be low for two reasons:

Because there is a loss of calcium greater than normal by increasing its elimination through the kidney or because this mineral accumulates in different areas of the body, it cannot be used. Thus decreasing its concentration in the blood (the calcium can precipitate and accumulate outside and inside the blood vessels).

The second reason or cause why the level of calcium in the blood may be low is due to a lack of contribution to this mineral’s body. This may be due not only to a deficient intake of calcium or vitamin D (which is essential for that calcium is used) and diseases in which the parathyroid gland is affected, which is responsible for regulating the metabolism of calcium in the body.

Therefore, hypocalcemia can be caused by the following reasons:

Loss of calcium from the bloodstream

Precipitation of calcium out of blood vessels:

  • Acute hyperphosphatemia (increased blood levels of phosphorus ): kidney failure, administration of phosphates, rhabdomyolysis (the disease caused by muscle necrosis. which causes the release into the blood of substances that under normal conditions are inside the cells that make up muscle tissue), tumor lysis (massive release into the blood of certain substances –among which phosphorus is found– as a consequence of the death of tumor cells; this is one of the possible complications of chemotherapy ).
  • Acute pancreatitis (inflammation of the pancreas).
  • Bone metastases from certain tumors ( breast cancer, prostate cancer ).
  • ‘Hungry bones’ syndrome: characterized by the appearance of low blood levels of calcium, phosphorus, and magnesium. It is due to a sudden increase in bone mineralization, and it typically appears in those patients in whom the parathyroid gland, which is the one that regulates calcium and phosphorus metabolism, has been surgically removed.

Decreased entry of calcium into the circulation

  • Alterations in PTH (the parathyroid hormone is a protein hormone secreted by the parathyroid gland that participates in the regulatory function of calcium and phosphorus metabolism. Increased PTH causes hypercalcemia (increased calcium concentration in the blood), while that its deficit causes hypocalcemia:
  • PTH deficiency:
  • Congenital hypoparathyroidism (PTH deficiency present from birth): Among the genetic diseases that cause congenital hypoparathyroidism, the DiGeorge syndrome stands out.
  • Acquired hypoparathyroidism (acquired during life, not present from birth): postsurgical (after neck surgeries), autoimmune, infiltrative diseases (tumors), depot diseases ( hemochromatosis, Wilson’s disease ), HIV, iodine irradiation, infarction of the parathyroid glands.
  • Alterations in PTH.
  • Resistance to the action of PTH (that is, there is enough PTH, but the body does not respond to it).