Background
Most all ( 99%) of calcium in the body is contained in the bones, but this mineral is critical in many other important ways. It is involved in normal enzyme function, skeletal and cardiac muscle contraction, normal heart rhythm and blood clot formation. The amount of calcium found in the blood is very tightly controlled to avoid malfunction of these important body functions. The body adjusts how much calcium is taken from the bones and absorbed in the bowel to help maintain a normal level in the blood which varies slightly from lab to lab but is typically between 8.5 and 10.2 mg/dL.
To maintain a normal blood level of calcium while maintaining normal bone strength a person needs to consume about 1,500 mg of calcium each day in the diet. This dietary intake combined with the regulation by two hormones, parathyroid hormone (PTH) and calcitonin, allows the body to maintain these normal levels.
PTH is produced by four small parathyroid glands located in the neck. When the calcium level in the blood drops, more PTH is produced which does several things to the body:
- Stimulates bones to release calcium into the blood
- Causes the kidneys to lose less calcium in the urine
- Stimulates the bowel to absorb more calcium into the blood
- Activates vitamin D in the kidneys causing the bowel to absorb more calcium
Calcitonin is produced by the thyroid gland and lowers calcium when it is elevated by slowing the breakdown of bone and release of calcium into the blood.
HypoCalcemia (Low Calcium)
Having a blood calcium level below the normal lab range. (below 8.5 mg/dL)
Causes
- Problem with the parathyroid glands
- Too little calcium in diet
- Certain kidney disorders
- A number of drugs can cause low calcium including rifampin (an antibiotic), anticonvulsants (such as phenytoin and phenobarbital), bisphosphonates (such as alendronate, ibandronate, risedronate, and zoledronic acid), calcitonin, chloroquine, corticosteroids, and plicamycin
- A low blood magnesium level (alcoholism)
- Vitamin D deficiency
- Bowel problems resulting in too little calcium absorption
- Pancreatitis (Infection/Inflammation of the pancreas)
Symptoms
If severe enough or prolonged it can result in confusion, memory loss, delirium, depression and hallucinations. At extremely low levels it may cause tingling, muscle aches and spasms of the throat muscles leading to breathing difficulty, muscle stiffness (tetany), seizures and abnormal heart rhythms.
Treatment
Often simply taking calcium and vitamin D supplements restore normal levels if calcium. If there is an underlying cause that needs to be corrected before any treatment will be durable. A common diuretic (hydrochlorothiazide) may be used to decrease the release of calcium by the kidneys to help correct the condition as well.