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# Hypoparathyroidism (incl. post-thyroidectomy hypocalcaemia)

The [parathyroid glands](https://durgical.com/en/anatomy/parathyroid-glands/) make too little hormone, so blood calcium falls. It most often follows neck surgery and causes tingling and muscle spasms.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Parathyroid glands](https://durgical.com/en/anatomy/parathyroid-glands/)
- [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/)
- [Inferior thyroid artery](https://durgical.com/en/anatomy/inferior-thyroid-artery/)
- [Superior thyroid artery](https://durgical.com/en/anatomy/superior-thyroid-artery/)
- [Recurrent laryngeal nerves](https://durgical.com/en/anatomy/recurrent-laryngeal-nerve/)

## In embryology

- [Pharyngeal pouches: tonsil, thymus, parathyroids and C cells](https://durgical.com/en/embryology/pharyngeal-pouches-tonsil-thymus-parathyroids-and-c-cells/)
- [22q11.2 deletion (DiGeorge): the third and fourth pouches](https://durgical.com/en/embryology/22q11-2-deletion-the-third-and-fourth-pouches/)

## Why it happens

- [Calcium regulation: PTH, vitamin D and calcitonin](https://durgical.com/en/physiology/calcium-regulation-pth-vitamin-d-and-calcitonin/)
- [The nerve action potential](https://durgical.com/en/physiology/the-nerve-action-potential/)
- [The ECG in potassium and calcium disorders](https://durgical.com/en/physiology/the-ecg-in-potassium-and-calcium-disorders/)
- [Thyroid follicles, C cells and parathyroid](https://durgical.com/en/histology/thyroid-follicles-c-cells-and-parathyroid/)

## What it is

A deficiency of parathyroid hormone (PTH) causing low blood calcium and high phosphate. The most common cause is injury to or removal of the parathyroid glands during thyroid or neck surgery. Pseudohypoparathyroidism is a related disorder in which PTH is high but the tissues do not respond to it.

## Who gets it

Transient low calcium is common after total thyroidectomy; permanent hypoparathyroidism occurs in a small proportion of patients and is more frequent after extensive cancer surgery or with less experienced surgeons. Non-surgical forms are rare.

## Causes

- Removal, bruising or devascularisation of the parathyroids during thyroidectomy, parathyroidectomy or neck dissection
- Autoimmune destruction, isolated or as part of autoimmune polyglandular syndrome type 1
- Congenital absence (DiGeorge syndrome, 22q11.2 deletion)
- Severe magnesium deficiency or excess, which impairs PTH secretion and action
- Infiltration (haemochromatosis, Wilson disease) or neck radiotherapy

## Risk factors

- Total thyroidectomy, especially for cancer, Graves disease or large goitre
- Repeat neck surgery or central lymph node dissection
- Low vitamin D before surgery
- Autoimmune disease or a family history of polyglandular syndrome

## Pathophysiology

Without PTH, bone releases less calcium, the kidney loses calcium and keeps phosphate, and less active vitamin D (calcitriol) is made, so intestinal calcium absorption falls. Low ionised calcium lowers the threshold for nerve depolarisation, causing neuromuscular irritability, and prolongs the QT interval.

## Classification

- Post-surgical: transient (recovers within months) or permanent
- Non-surgical: autoimmune, genetic, infiltrative or due to magnesium disorders
- Pseudohypoparathyroidism: PTH resistance with high PTH; type 1a has Albright hereditary osteodystrophy (short stature, short fourth and fifth metacarpals)

## Symptoms and signs

- Tingling around the mouth and in the fingers and toes
- Muscle cramps and carpopedal spasm
- Positive Chvostek sign (facial twitch on tapping the [facial nerve](https://durgical.com/en/anatomy/facial-nerve/)) and Trousseau sign (hand spasm with a blood pressure cuff inflated)
- Fatigue, anxiety, depression and difficulty concentrating
- Long-standing disease: cataracts, basal ganglia calcification, dry [skin](https://durgical.com/en/anatomy/skin/) and brittle nails

## Red flags

- Laryngospasm or stridor after thyroid surgery
- Seizures
- QT prolongation, arrhythmia or heart failure
- Rapidly progressing tetany

## Diagnosis

**Clinical**
History of neck surgery or autoimmune disease, and bedside Chvostek and Trousseau signs. After thyroidectomy, nurses monitor for perioral tingling, cramps and airway compromise.

**Tests**
Low total or ionised calcium (corrected for albumin), high phosphate, and low or inappropriately normal PTH; magnesium and 25-hydroxyvitamin D. ECG for QT prolongation. Urinary calcium during treatment.

**Imaging**
Not needed for diagnosis. Brain CT may show basal ganglia calcification and [kidney](https://durgical.com/en/anatomy/kidney/) ultrasound may show nephrocalcinosis in long-standing disease.

## Differential diagnosis

- Vitamin D deficiency (PTH high, phosphate low)
- Hypomagnesaemia
- Chronic kidney disease (PTH high)
- Pseudohypoparathyroidism (PTH high)
- Hungry bone syndrome after parathyroidectomy and acute pancreatitis

## Goal of treatment

Relieve symptoms and keep calcium in the low-normal range while avoiding hypercalciuria, kidney stones and nephrocalcinosis.

## Treatment

**Acute**
Severe or symptomatic hypocalcaemia: intravenous calcium gluconate with cardiac monitoring, plus correction of low magnesium.

**Medical**
Long-term oral calcium and active vitamin D (calcitriol); thiazide diuretics can reduce urinary calcium; recombinant PTH in selected patients not controlled with standard therapy.

**Follow-up**
Serial calcium after thyroidectomy, then periodic calcium, phosphate, magnesium, creatinine and urinary calcium; seizure and airway precautions on the ward.

## Complications

- Tetany, seizures and laryngospasm
- Arrhythmias and heart failure from prolonged QT
- Cataracts and basal ganglia calcification
- Kidney stones, nephrocalcinosis and reduced kidney function from treatment

## Prognosis

Transient post-operative hypocalcaemia usually resolves within weeks to months. Permanent disease needs lifelong treatment and monitoring; quality of life is often reduced even with normal calcium.

## Prevention

- Careful identification and preservation of the parathyroid glands and their blood supply during neck surgery
- Correcting vitamin D deficiency before thyroidectomy
- Early calcium or PTH measurement after total thyroidectomy

## Test yourself

Think of the answer, then tap the question to see it.

## What is the most common cause of hypoparathyroidism?

Damage to or removal of the parathyroid glands during thyroid or other neck surgery.

## Which two bedside signs suggest hypocalcaemia?

Chvostek sign (facial twitch on tapping the facial nerve) and Trousseau sign (carpal spasm with an inflated blood pressure cuff).

## What pattern of calcium, phosphate and PTH defines hypoparathyroidism?

Low calcium, high phosphate and low or inappropriately normal PTH.

## Which electrolyte must be corrected for hypocalcaemia to respond to treatment?

Magnesium, because hypomagnesaemia impairs PTH secretion and action.

## What ECG change is typical of hypocalcaemia?

A prolonged QT interval.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/hypoparathyroidism/)

## Related conditions

- [Thyroid cancer (papillary)](https://durgical.com/en/conditions/thyroid-cancer/)
- [Graves disease (hyperthyroidism)](https://durgical.com/en/conditions/graves-disease/)
- [Primary hyperparathyroidism](https://durgical.com/en/conditions/primary-hyperparathyroidism/)
- [Hypomagnesaemia](https://durgical.com/en/conditions/hypomagnesaemia/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Rickets and osteomalacia](https://durgical.com/en/conditions/rickets-and-osteomalacia/)
- [Long QT syndrome and torsades de pointes](https://durgical.com/en/conditions/long-qt-syndrome-and-torsades-de-pointes/)
- [Cataract](https://durgical.com/en/conditions/cataract/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Hypoparathyroidism](https://medlineplus.gov/ency/article/000385.htm) (MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/hypoparathyroidism/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/hypoparathyroidism/