Hypoparathyroidism

Question 1

Definition of Hypoparathyroidism

Answer 1

Disorder caused by the relative or absolute deficiency of PTH synthesis and secretion. This would lead to low serum calcium and elevated serum phosphate

Question 2

Aetiology of Hypoparathyroidism

Answer 2

• Primary Hypoparathyroidism:
• DECREASE in PTH secretion due to gland failure
• Would lead to LOW CALCIUM and HIGH PHOSPHATE
• Can be due to:
◦ Autoimmune
◦ Congenital (di George)

• Secondary Hypoparathyroidism:
• As a result of:
◦ Radiation
◦ Surgery (thyroidectomy, parathyroidectomy)
◦ Hypomagnesaemia (Mg needed to secrete PTH)

• Pseudohypoparathyroidism:
• Due to TARGET CELLS being INSENSITIVE to PTH
• Associated with low IQ, short stature and shortened metacarpals (4th and 5th)
• Leads to LOW CALCIUM, HIGH PHOSPHATE BUT HIGH PTH
• Due to genetics

• Pseudopseudohypoparathyroidism:
◦ Similar presentation to pseudohypoparathyroidism, but normal biochemistry
◦ Due to genetics

Question 3

History and Examination of Hypoparathyroidism

Answer 3

• Hypocalcaemia symptoms:
• Convulsions: acute or severe hypocalcaemia
• Arrhythmias: prolonged QT interval (increases risk of tachyarrhythmias)
• Tetany: Muscle twitches, spasms, cramps
• Paraesthesia: numbness, tingling, pins and needles. Can get in perioral region
• Poor memory, slowed thinking
• Chvosteks sign: Contraction of facial muscles when facial nerve tapped in front of ear
• Trousseaus sign: carpal spasm when BP cuff inflated above systolic pressure

Question 4

Risk factors for Hypoparathyroidism

Answer 4

• Thyroid surgery
• Parathyroid surgery
• Chronic alcoholism (can lead to reduced Mg)

Question 5

Investigations for Hypoparathyroidism

Answer 5

• Serum calcium: would be decreased
• Serum albumin: low albumin will give falsely low calcium, ensure it is normal
• Plasma intact PTH: low in primary, normal/high in pseudo
• Serum phosphorus: likely to be elevated
• Serum Mg: may be low
• ECG: can show prolonged QT interval

Question 6

Treatment of Hypoparathyroidism

Answer 6

Severe symptomatic hypocalcaemia:
1) IV calcium: give calcium gluconate

Asymptomatic hypocalcaemia:
1) Oral calcium + Calcitriol: can give Calcium carbonate and vitamin D supplements

Question 7

Prevention and prognosis of Hypoparathyroidism

Answer 7

Reduce unintended surgical removal or damage to the parathyroid gland or its blood supply

Good prognosis if managed well. But there are risk of over-compensating for the calcium and vitamin D levels

Question 8

Complications of Hypoparathyroidism

Answer 8

• Ectopic calcifications: can occur in soft tissues, organs etc
• Cataracts
• Renal insufficiency
• Hypercalcaemia: due to over-treatment