Hypoparathyroidism

Question 1

what are the acquired causes of hypoparathyroidism?

Answer 1

• iatrogenic
• infiltration of the parathyroid glands (e.g. haemochromatosis, wilson’s disease)
• radiation
• functional (e.g. hypermagnesaemia, hypomagnesaemia)
• transient (e.g. alcoholism, burns)

Question 2

what are the congenital causes of hypoparathyroidism?

Answer 2

• DiGeorge syndrome
• autoimmune polyendocrine syndrome type 1 (APS-1)
• hypoparathyroidism, deafness and renal (HDR) dysplasia genetic syndrome

Question 3

what is pseudohypoparathyroidism?

Answer 3

• a rare inherited disorder with target organ resistance to PTH, resulting in low serum calcium and high phosphate, with a high PTH

Question 4

what is albright’s hereditary osteodystrophy?

Answer 4

a characteristic pattern of skeletal abnormalities, associated with the commonest form of pseudohypoparathyroidism (type 1a):

• short stature
• round face
• obesity
• short metacarpals

Question 5

what are the risk factors for hypoparathyroidism?

Answer 5

• anterior neck surgery
• hypomagnesaemia (e.g. alcoholism, malabsorption, PPIs)
• iron deposition (e.g. haemochromatosis, frequent blood transfusions)
• copper deposition (e.g. wilson’s disease)
• malignancy (e.g. metastases)

Question 6

what are the symptoms of hypocalcaemia?

Answer 6

• paraesthesia (e.g. fingers, toes, lips)
• cramps
• carpopedal spasm
• stridor (e.g. due to laryngospasm)
• tetany
• seizures

Question 7

what are the signs on examination of hypocalcaemia?

Answer 7

• chvostek’s sign (e.g. elicited by tapping on the facial nerve in front of the ear; twitching of the corner of the mouth indicates a positive result)
• trousseau’s sign (e.g. elicited by occluding the blood supply to the arm by inflation of a blood pressure cuff above the arterial pressure for 3 minutes; carpopedal spasm is induced in a positive result)
• dental abnormalities / enamel dysplasia
• dry skin
• brittle nails

Question 8

what are the investigations for hypoparathyroidism?

Answer 8

• ECG (e.g. prolonged QT interval may be present)
• serum PTH
• corrected calcium
• phosphate
• vitamin D
• U&Es
• magnesium
• ? US KUB
• ? MRI brain

Question 9

what is the acute management of severe hypocalcaemia?

Answer 9

10–20 mL of 10% calcium gluconate in 50–100 mL of 5% glucose IV over 10 minutes

if there is concurrent hypomagnesaemia, then this should also be corrected with IV magnesium sulphate

Question 10

what is the management of hypoparathyroidism?

Answer 10

• active vitamin D analogue (e.g. calcitriol, alfacalcidol)
• calcium-rich diet
• ? calcium supplementation
• ? PTH

Question 11

what are the long-term complications of hypoparathyroidism?

Answer 11

• cardiovascular (e.g. QTc prolongation, cardiac arrhythmia, death)
• CKD
• renal calculi
• cataracts
• neuromuscular (e.g. seizure, tetany, stiffness)
• neuropsychiatric (e.g. anxiety, depression)
• basal ganglia calcification