Hypoparathyroidism

Question 1

What is Hypoparathyroidism?

Answer 1

• characterised by hypocalcaemia, hyperphosphataemia and low or inappropriately normal levels of parathyroid hormone (PTH)

Question 2

What are the functions of PTH?

Answer 2

• Increase bone resorption
• conversion of 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3
• reduce phosphate resorption
• Function of activated vit D
  
  • intestinal calcium absorption
  • DCT calcium reabsorption

Question 3

What causes hypoparathyroidism?

Answer 3

• anterior neck surgery (most common)
• Transient hypoparathyroidism in the neonatal period
  • reduction in serum calcium levels by 24-48 hours of age
• DiGeorge’s syndrome
  
  • abnormal development of the parathyroid glands from the third and fourth pharyngeal pouches

*hypoparathyroidism very rare

Question 5

What is pseudohypoparathyroidism?

Answer 5

• no endocrine abnormality but the morphological features are otherwise the same as for pseudohypoparathyroidism
• end-organ resistance to the action of PTH.

Question 6

What are the sx of hypoparathyroidism?

*think hypocalcaemia

Answer 6

• Muscle pains.
• Bone pain
• Abdominal pain.
• Paraesthesiae of the face, fingers and toes.
• Facial twitching
• Lethargy.
• Headaches.
• Brittle nails.
• Dry hair and skin.
• Painful menstruation

Question 7

What are the clinical signs of hypoparathyroidism?

Answer 7

• Chvostek’s sign (contraction of facial muscles by light tap on facial nerve)
• Trousseau’s sign (carpopedal spasm due to sphygmomanometer cuff)
• Raised intracranial pressure with papilloedema.
• Cataracts

*

Question 8

What are the differential diagnosis for hypoparathyroidism?

*think what causes hypocalcaemia and hyperphosphataemia

Answer 8

• Magnesium deficiency.
• Vitamin D deficiency.
• Chronic kidney disease:

Question 9

What Ix would you order for hypoparathyroidism?

Answer 9

Bloods

• Low serum calcium.
• High serum phosphate.
• Low PTH.
• Normal alkaline phosphatase
• Serum magnesium: may be low
• U&Es: to exclude chronic kidney disease
• 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3

Other

• ECG: prolonged QT interval
• Echocardiogram: DiGeorge Syndrome
• Renal ultrasound - see renal calculi
• Brain MRI scan: basal ganglia calcification

Question 11

What will the blood results look like for pseudohypoparathyroidism?

Answer 11

• Low serum calcium.
• High or normal PTH.

Question 12

How would you mx hypoparathyroidism?

Answer 12

• If severe hypocalcaemia
  
  • Urgent IV Calcium
• Diet advice: HIgh Calcium & Vit D
• Close monitoring of Ca
• PTH replacement
• Surgery
  
  • Parathyroid autotransplantation and allotransplantation

Question 13

What are the Cx of hypocalcaemia?

Answer 13

• Laryngospasm > stridor and airway obstruction.
• Neuromuscular irritability can lead to muscle cramps, tetany and seizures.
• Heart: QT interval changes can cause syncope, arrhythmias and death.
• Calcium can be deposited in the kidneys, causing calculi.
• Stunted growth, malformed teeth and mental impairment can develop if untreated in childhood.
• Over-treatment with vitamin D can cause hypercalcaemia and renal impairment