How hypoparathyroidism affects the entire body

The thyroid is a butterfly-shaped gland located in the front of the neck that produces hormones that regulate many important processes in the body.

Located directly behind the thyroid are the parathyroid glands. These are four pea-shaped glands that produce parathyroid hormone (PTH). This hormone controls calcium and phosphate levels in the blood.

Hypoparathyroidism is a disorder where the parathyroid glands produce insufficient amounts of PTH, leading to low levels of calcium and also elevated levels of phosphate, and a wide range of potential symptoms and complications.

The critical role of calcium

Calcium is the most abundant mineral in the human body. The body cannot synthesize calcium, and it is acquired in the foods a person consumes. About 99 percent of the calcium in the body is stored in bones and in teeth, and calcium helps teeth and bones maintain their hardness, strength, and structure.

At any given time, about 1 percent of the calcium in the body is located in blood and tissues. Parathyroid hormone transports calcium from bones into the bloodstream, helping the body maintain this balance.

Calcium plays a critical part in several important functions throughout the body:

• Muscle contraction and relaxation
• Nerve signaling
• Regulation of blood pressure
• Heart rate
• Hormone activation

Calcium is constantly moving in and out of cells through access points called calcium channels. As a calcium molecule enters a cell, it triggers a response. For example, muscle contractions occur as calcium enters a muscle cell and attaches to a protein called troponin (and muscles relax as calcium detaches from troponin).

This includes skeletal muscles (like the muscles in the arms and legs), the cardiac muscle that controls the pumping of the heart, and the smooth muscle cells that allow blood vessels to tighten and relax, regulating blood pressure.

Nerve cells (neurons) and the cells that make up hormone-producing glands (endocrine cells) also have calcium channels, and calcium plays a critical role in the release of neurotransmitters and hormones that regulate countless functions throughout the body.

Keep in mind that this is a simplified explanation of complex and interconnected biological processes.

The relationship between PTH and phosphate

As mentioned above, hypoparathyroidism also leads to elevated levels of phosphate in the blood. PTH acts on the kidneys, promoting reabsorption of calcium into the bloodstream and the excretion of phosphate in urine. When there is insufficient PTH, calcium is directed into urine while phosphate is reabsorbed back into the bloodstream.

Elevated phosphate levels further lower calcium levels, creating a cycle of calcium loss. It is the combined effect of low calcium and high phosphate that drives symptoms and complications.

Hypoparathyroidism can affect many parts of the body

Systems throughout the body rely on a delicate balance of these minerals in order to function normally. When a condition like hypoparathyroidism disrupts this balance, many organs and systems can be affected, leading to a wide range of symptoms and potentially serious complications.

Common symptoms include:

• Tingling, numbness, or burning sensations in the fingers, toes, and/or around the mouth
• Muscle aches, cramps, and/or spasms, often in the feet, legs, abdomen and/or face
• Cognitive symptoms like brain fog and difficulties with thinking, memory, and concentration
• Headaches
• Abdominal pain
• Fatigue
• Dry skin, hair, and nails
• Painful menstruation

Hypoparathyroidism can also lead to serious complications:

• Kidney stones and chronic kidney disease
• Airway spasms that affect breathing
• Seizures and/or difficulty with balance and movement
• Mood disorders like anxiety and depression
• Heart arrhythmias, cardiomyopathy, narrowing/stiffening of blood vessels, and heart failure
• Weakened bones and increased fractures
• In children: developmental delays, problems with tooth development, poor growth, changes in the shape of bones

Treatment for hypoparathyroidism

The most common cause of hypoparathyroidism is injury to the parathyroid glands during surgery, such as surgery on the nearby thyroid gland. Hypoparathyroidism can also occur as a result of genetic disorders, autoimmune disease, being born without parathyroid glands or nonfunctioning parathyroid glands, and magnesium deficiency.

Treatment for hypoparathyroidism will depend on the cause, as well as symptoms, disease severity, lab tests, overall health, and other factors.

For hypoparathyroidism caused by magnesium deficiency, correcting the magnesium deficiency will be the primary treatment.

In other cases, the main treatment is supplements of calcium and vitamin D to maintain an appropriate balance of calcium and phosphate. Some people may also be prescribed parathyroid replacement therapy in addition to calcium and vitamin D supplements. Sometimes, high-calcium/low-phosphate diets may be recommended.

Monitoring of calcium levels, phosphate levels, and kidney function are essential parts of all treatment plans.