Hypoparathyroidism is characterized by low blood levels of parathyroid hormone (PTH), a crucial regulator of calcium levels and of vitamin D production.
As a result, people with hypoparathyroidism have low levels of calcium, a condition called hypocalcemia, and high levels of phosphorus in the blood.
The disease is usually diagnosed through physical evaluation, a review of family history, and blood and urine tests.
Recognizing the typical signs and symptoms of hypocalcemia can be key in diagnosing hypoparathyroidism and in monitoring response to treatment.
Signs of hypoparathyroidism obtained through a physical exam mainly include twitching or spasms of muscles — especially those in the lips, hands, feet, and throat — as well as muscle cramps, usually in the legs and feet. Likewise, people with this condition tend to have unusually dry skin and brittle nails.
Physical assessment also includes asking a patient about a previous neck surgery, particularly thyroid surgery, or looking to identify a scar indicating such surgery. Neck surgery — as well as cancer radiation treatment to the neck or face — is known to be one of the causes of acquired hypoparathyroidism, as it can damage the parathyroid glands.
A skin examination is also important to identify candidiasis, a fungal infection caused by a yeast (a type of fungus), and vitiligo — where patches of skin lose color. These symptoms are suggestive of autoimmune polyendocrine syndrome type 1, an inherited condition whose manifestations can include autoimmune hypoparathyroidism. This disease form occurs when the immune system mistakenly attacks the parathyroid glands and prevents them from producing PTH.
Symptoms such as growth failure, hearing loss, or slower mental development in children suggest a genetic cause for hypoparathyroidism.
Clinical and family history
A detailed medical history is crucial in the diagnosis of hypoparathyroidism. This comprises clinical history, including the occurrence of surgeries, previous radiation therapy, or the presence of other conditions.
The family health history, which is a record of the diseases or health conditions in a particular family, is also considered in diagnosing hypoparathyroidism. A full record includes information from three generations of relatives, including children, brothers and sisters, parents, aunts and uncles, nieces and nephews, grandparents, and cousins.
The existence of hypoparathyroidism in a family suggests the disease has a genetic cause.
Blood and urine tests
Blood tests examine the levels of several minerals and molecules, including PTH, calcium, phosphorus, magnesium, and vitamin D.
Usually, hypoparathyroidism is diagnosed when a blood test shows low levels of PTH, vitamin D, calcium, and magnesium, as well as high levels of phosphorus.
Urine tests are used to determine the amount of calcium being excreted. An unusual loss of calcium through urine may indicate the presence of hypoparathyroidism, as it can result from low PTH.
During treatment, patients undergo regular lab tests to ensure that levels of essential minerals and molecules remain constant and within normal ranges.
Genetic testing uses a small blood sample to look for mutations in a person’s DNA.
It may be used to confirm diagnosis, as it detects mutations in genes known to cause the disease. Notably, familial isolated hypoparathyroidism can be caused by mutations in the calcium-sensing receptor (CASR) gene, in the PTH gene encoding the hormone, and others.
Additional tests may be required to determine if you have health problems that could be related to hypoparathyroidism.
One such test is an electrocardiogram — a painless test of the electrical activity of the heart — used to detect arrhythmias, or heart rhythm problems, a condition that has been related to hypocalcemia and hypoparathyroidism.
An eye exam may also be done to check for cataracts — when the eye’s natural lens becomes cloudy — another well-known problem of hypoparathyroidism.
X-rays and bone density tests (a kind of X-ray) can help to determine if low calcium levels have affected the bones. PTH regulates calcium levels in the bones, which is essential for bone remodeling — a process in which old bone is replaced by new bone. This means that low PTH in hypoparathyroidism can lead to poorer bone remodeling and greater bone density (or mass), which may raise a patient’s risk of fractures.
Last updated: April 12, 2021
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