Calcium is crucial for the normal functioning of all the cells in the body. Its level in the blood is maintained within a very narrow range, through the combined effect of parathyroid hormone, vitamin D and the kidneys. Hypocalcemia, or low blood calcium, is most often caused by a deficiency of parathyroid hormone. The effects of hypocalcemia depend on its severity, and on how fast it develops. Hypocalcemia can be asymptomatic; it can be a life-threatening condition.
Neuromuscular Symptoms
Low levels of calcium in the blood increase the excitability of nerves and muscles. Symptoms include twitching of the facial muscles, which can be elicited by tapping the face in front of the ear. Numbness and tingling in the fingertips and around the mouth may occur, even with mild hypocalcemia. More severe hypocalcemia causes tetany, or prolonged contraction of muscles. The hands contract in a specific pattern known as carpopedal spasms and muscles cramps may occur. The muscles controlling respiration and the muscles that keep the airway open may be affected, leading to difficulty breathing.
Neurological Symptoms
Hypocalcemia can cause seizures. Dementia may occur in adults, while children may suffer from mental retardation. Psychiatric symptoms include anxiety and depression. Areas of the brain responsible for involuntary movement may become calcified, leading to symptoms resembling those of Parkinson's disease, such as tremor and rigidity. Confusion and hallucinations may appear.
Cardiac Effects
Acute hypocalcemia can prolong the period it take heart muscles to get ready to contract again. The EKG will show a prolonged QT interval. This effect predisposes the patient to life-threatening disturbances in the heart rhythm. Other cardiac effects include cardiomyopathy, or disease of the heart muscle, and low blood pressure.
Other Symptoms
Gastrointestinal symptoms may occur, including difficulty swallowing. Reduced acid secretion in the stomach can lead to malabsorption of several nutrients. The skin may become coarse, dry and with excessive pigmentation, which is different from the person's usual skin tone. Cataracts may develop.
References
- Clevelandclinicmeded.com: Hypocalcemia
- "Harrison's Principles of Internal Medicine"; Anthony Fauci et al.; 2008
