What Causes Nonsurgical Hypoparathyroidism in Adults?

Most cases of hypoparathyroidism happen when the parathyroid glands are damaged or removed during neck surgery. “Nonsurgical hypoparathyroidism” refers to cases where there is no history of neck surgery. It requires a medical evaluation to confirm the diagnosis and investigate whether the cause is genetic, autoimmune, magnesium-related, or due to other factors ^[1].

Important Safety Note: If you experience severe muscle cramps, spasms, tingling, confusion, seizures, or difficulty breathing, seek urgent medical care for potentially severe low calcium (hypocalcemia).

Autoimmune Conditions

Autoimmune damage to the parathyroid glands is a major cause of nonsurgical hypoparathyroidism ^[2].

• Isolated autoimmune hypoparathyroidism: Sometimes, the immune system only attacks the parathyroid glands. Because routine antibody blood tests cannot reliably confirm this, it is often a “diagnosis of exclusion”—meaning your doctor determines you have it by ruling out other causes first ^[3].
• Autoimmune polyglandular syndrome type 1 (APS-1): This is a rare genetic condition where the immune system attacks multiple organs ^[4]. In addition to hypoparathyroidism, people with APS-1 often develop chronic yeast infections (candidiasis) and adrenal gland insufficiency (Addison’s disease) ^[5]. Note: Adrenal insufficiency can be life-threatening. Seek immediate emergency care for severe weakness, vomiting, fainting, or very low blood pressure.

Genetic and Syndromic Causes

Some cases are caused by genetic changes. These may be diagnosed in childhood, but some are discovered in adulthood ^[6][7].

• 22q11.2 Deletion Syndrome (DiGeorge Syndrome): Occurs when a small piece of chromosome 22 is missing, leading to poorly developed parathyroid glands ^[8]. It can also cause heart defects, immune system issues, and highly variable physical features ^[9].
• Autosomal Dominant Hypocalcemia Type 1 (ADH1): Caused by a variation in the CASR gene, which makes the body overly sensitive to calcium levels and suppresses PTH production ^[10][11]. People with ADH1 often excrete high amounts of calcium in their urine, increasing the risk of kidney stones. Standard calcium treatments can worsen this complication, so specialist management is required ^[12].
• Barakat (HDR) Syndrome: Caused by changes in the GATA3 gene, this syndrome features a combination of hypoparathyroidism, sensorineural hearing loss, and kidney anomalies ^[13][14].
  (Note: Other rare genetic causes exist, and sometimes a definitive genetic cause is never found.)

Other Acquired Causes

• Severe Magnesium Deficiency: Magnesium is essential for the parathyroid glands to release PTH ^[1]. If your magnesium drops too low—often due to prolonged use of proton-pump inhibitors (acid reflux medications), diuretics (water pills), alcohol use, or chronic diarrhea—your glands temporarily stop working. This causes a functional, reversible suppression of PTH; restoring magnesium levels under medical supervision usually resolves this temporary hypocalcemia ^[15].
• Radiation Therapy: Prior radiation exposure to the neck (such as treatment for certain cancers) can gradually damage the parathyroid glands ^[2][16].
• Infiltrative Diseases: Rarely, severe iron overload (often from repeated blood transfusions) or copper overload can build up and damage the glands ^[2][16].

How Your Doctor Investigates the Cause

Because there are many possible reasons for nonsurgical hypoparathyroidism, your doctor will conduct a step-by-step evaluation.

Medical History and Physical Exam

Your doctor will ask about your family history, age when symptoms began, and any prior neck radiation or medications that could affect magnesium ^[1]. They will also check for clues like hearing problems or signs of other autoimmune diseases ^[17].

Confirming the Diagnosis with Blood and Urine Tests

To establish chronic nonsurgical hypoparathyroidism, doctors typically check your blood on at least two separate occasions. They look for low calcium (specifically ionized calcium or albumin-adjusted calcium) and high phosphorus alongside a low or “inappropriately normal” PTH level ^[18]. Normally, if calcium is low, PTH should rise. If PTH stays in the “normal” range while calcium is low, the parathyroid glands are not responding properly.

• Magnesium, Kidney Function, and Vitamin D: Assessing these is critical to rule out other causes of low calcium ^[1].
• High PTH: If your PTH level is very high, it points away from primary parathyroid gland failure. It could indicate Vitamin D deficiency, kidney disease, or a rare condition called pseudohypoparathyroidism (where the body resists PTH) ^[19][18].
• Urine Tests: Checking urine calcium is important, especially to screen for conditions like ADH1 or to monitor kidney health, as hypoparathyroidism alters how the kidneys handle calcium ^[18].

Imaging and Genetic Testing

• Imaging: Your doctor may order a kidney ultrasound to look for kidney stones or calcium deposits (nephrocalcinosis), which are common complications ^[20]. A brain CT scan to check for calcium deposits in the brain (basal ganglia calcifications) is not routine; it involves radiation and is usually only ordered if you have specific neurological symptoms like seizures or movement issues ^[21][22].
• Genetic Testing: If you were diagnosed at a young age, have a family history, or have other syndromic features (like hearing loss), your doctor may recommend genetic testing (like a chromosomal microarray or targeted gene panel) and genetic counseling to help you and your family understand the results ^[17][9].