Hypoparathyroidism (E&M) Flashcards
Define hypoparathyroidism.
Disorder caused by relative or absolute deficiency of PTH synthesis and secretion, leading to low serum calcium and elevated serum phosphate
What are the main causes of hypoparathyroidism? (4)
- postoperative - thyroidectomy, parathyroidectomy, laryngeal surgery, transient postoperative hypocalcaemia
- autoimmune
- nonautoimmune - Wilson disease, haemochromatosis
- congenital - DiGeorge syndrome
What is pseudohypoparathyroidism?
Rare genetic condition resulting in failure of target organs to respond to normal levels of parathyroid hormone
What are some clinical features of pseudohypoparathyroidism? (4)
- short stature
- short fingers
- symptoms of hypocalcaemia
- vitamin D deficiency
What condition can develop into hypoparathyroidism?
Riedel thyroiditis
What are the clinical features of hypoparathyroidism generally in line with?
Hypocalcaemia (increased neuromuscular excitability) - CATS go numb
(Convulsions, Arrhythmias, Tetany/Spasms, Paraesthesia)
What are the clinical features of hypoparathyroidism? (4+4)
- convulsions
- arrhythmias (prolonged QT interval)
- tetany - muscle twitches, spasms, cramps
- paraesthesia, numbness, tingling
- malnutrition, malabsorption, diarrhoea
- chronic alcoholism
- poor memory + slowed thinking
- dry nails, brittle hair, cataracts
What might we see on examination of hypoparathyroidism?
- Chvostek’s sign - contraction of facial muscles when facial nerve is tapped in front of ear
- Trousseau’s sign - painful clasping response of fingers and hands (carpopedal spasm) when BP cuff is inflated above systolic BP
What other electrolyte abnormality has the same features as hypoparathyroidism?
Hypomagnesaemia
What are some risk factors for hypoparathyroidism? (4)
- thyroid/parathyroid surgery
- hypomagnesaemia
- moderate and chronic maternal hypercalcaemia (neonatal hypocalcaemia)
- autosomal dominant conditions
What are the first-line investigations for hypoparathyroidism? (4)
- serum calcium
- plasma intact PTH
- serum albumin
- ECG
What important blood findings are there in hypoparathyroidism? (6)
- low PTH
- low serum calcium (and normal ALP)
- high serum phosphate
- normal serum albumin (low albumin = falsely low serum calcium)
- normal/low serum magnesium
- normal/low 25-OH vitamin D
What would ECG show in hypoparathyroidism?
Isolated prolonged QT interval (predisposes to Torsades de Pointes)
Indicates severe life-threatening hypocalcaemia, treat with urgent IV calcium gluconate
What are some differential diagnoses for hypoparathyroidism? (5)
- hypovitaminosis D - PTH high, vitamin D low
- hypomagnesaemia - low serum Mg
- hypoalbuminemia
- pseudohypoparathyroidism - elevated plasma intact PTH, target organs cannot respond
- CKD/renal failure - elevated serum creatinine and PTH
How do we manage hypoparathyroidism? (2)
IV/oral calcium AND low dose calcitriol
Consider: human recombinant PTH + adjustment of calcium and/or calcitriol doses (in chronic disease)
