Is decreased function of the parathyroid glands with underproduction of parathyroid hormone. This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany (involuntary muscle contraction), and several other symptoms.
Symptoms:
Tingling or burning (paresthesias) in your fingertips, toes and lips
Muscle aches or cramps affecting your legs, feet, abdomen or face
Twitching or spasms of your muscles, particularly around your mouth, but also in your hands, arms and throat
Fatigue or weakness
Painful menstruation
Patchy hair loss, such as thinning of your eyebrows