Hypoparathyroidism arises when the body produces too little parathyroid hormone (PTH), disrupting calcium and phosphate balance. This rare condition has many causes. Some develop later in life, while others are genetic or present at birth. Knowing these causes helps doctors diagnose and manage the disorder better. Each cause affects treatment and outlook differently.
This section reviews the main causes of hypoparathyroidism. It explains how parathyroid function is affected and how this changes symptoms and disease progress.
Post-Surgical Causes of Hypoparathyroidism
The most common cause of hypoparathyroidism is accidental injury or removal of the parathyroid glands during neck or thyroid surgery. This is called iatrogenic hypoparathyroidism.
- Thyroid Surgery
Operations to remove the thyroid for cancer, goitre, or hyperthyroidism may damage or remove the small parathyroid glands behind the thyroid. Even if the glands stay, blood flow may be affected, causing temporary or permanent problems. - Parathyroid Surgery
Sometimes surgery for too much parathyroid hormone (hyperparathyroidism) removes too much gland tissue, leading to low hormone levels. - Neck Dissections and Cancer Surgery
Surgeries removing lymph nodes or tumors in the neck may harm nearby parathyroid glands, especially in complex cancer operations.
Post-surgical hypoparathyroidism can last weeks or months or become permanent if all functioning glands are lost. This cause accounts for over 70% of adult cases in developed countries.
Autoimmune Causes of Hypoparathyroidism
Autoimmune hypoparathyroidism happens when the immune system attacks the parathyroid glands. It usually occurs as part of a larger autoimmune disease called Autoimmune Polyglandular Syndrome Type 1 (APS-1).
APS-1 typically starts in childhood or adolescence. It often includes Addison’s disease and chronic fungal infections of the skin and mucous membranes. Other conditions like diabetes, vitiligo, and reproductive failure may also occur.
In autoimmune cases, blood tests detect antibodies against proteins such as NALP5 or calcium-sensing receptors. These antibodies harm the glands. The disease may get worse over time, causing unstable calcium levels and neurological problems if not caught early.
Genetic and Congenital Causes
Some people are born with hypoparathyroidism due to genetic problems that affect gland development or hormone production.
- DiGeorge Syndrome (22q11.2 Deletion)
This syndrome causes missing or underdeveloped parathyroid glands. It also affects the heart, immune system, and facial features. - CaSR Mutation (Autosomal Dominant Hypocalcaemia)
Mutations in the calcium-sensing receptor gene trick the body into thinking calcium levels are too high. This stops PTH release even though calcium is low. Patients have normal gland structure but low hormone. - Isolated Hypoparathyroidism
Mutations in genes like GCM2 or PTH cause absent or defective hormone production despite normal glands. Symptoms often appear in infancy or early childhood, such as seizures or muscle spasms. - Syndromic Causes
Syndromes like Kenny-Caffey or HDR include hypoparathyroidism along with deafness, kidney problems, or other features.
Genetic testing helps diagnose these cases, guide treatment, and advise families.
Infiltrative and Metabolic Causes
Rarely, other diseases damage the parathyroid glands.
- Haemochromatosis
Iron overload causes iron deposits in glands, reducing function. This often affects the liver and pancreas too. - Wilson’s Disease
Copper builds up in tissues and can harm the parathyroids. - Thalassaemia Major
Frequent blood transfusions cause iron overload that can damage glands.
These diseases often cause multiple hormone problems and need team care.
Radiation-Induced Causes
Radiation treatment to the neck or chest, used for cancers like lymphoma, can damage parathyroids.
This damage may appear months or years later. High doses and repeated treatments increase risk. Children are especially sensitive due to growing glands.
Doctors should screen patients with past neck radiation for calcium problems and neuromuscular symptoms.
Functional or Transient Causes
Sometimes PTH drops temporarily without permanent gland damage.
- Magnesium Deficiency
Low magnesium stops PTH secretion and action. Causes include poor diet, alcoholism, or digestive losses. Fixing magnesium levels often restores normal hormone and calcium. - Postpartum Hypoparathyroidism
Rarely, pregnancy and childbirth cause temporary hypoparathyroidism, possibly due to hormonal or immune changes.
Idiopathic Hypoparathyroidism
Sometimes doctors find no cause despite full testing. These cases are called idiopathic.
New research may classify some idiopathic cases as autoimmune or genetic as tests improve.
Summary
Causes of hypoparathyroidism vary widely. Surgery, autoimmune disease, genetics, infiltrative illness, and temporary metabolic changes all play roles. Identifying the exact cause helps tailor treatment, predict outcomes, and assess family risk.
Post-surgical hypoparathyroidism remains the most common cause globally. Autoimmune and genetic forms often affect younger patients and those with syndromes.
Testing calcium, PTH, vitamin D, magnesium, and phosphate levels, plus imaging and genetic tests, forms the basis for correct diagnosis and care.
