Hypoparathyroidism Flashcards
What is hypoparathyroidism?
caused by relative or absolute deficiency of plasma parathyroid hormone (PTH) synthesis and secretion
What is primary hypoparathyroidism?
PTH secretion is low due to gland failure
What are the causes of primary hypoparathyroidism?
- Autoimmune
2. Congenital
What are causes of secondary hypoparathyroidism?
- Radiation
- Surgery (thyroidectomy, parathyroidectomy)
- Hypomagnesaemia (magnesium is required for OTH secretion)
What is pseudohypoparathyroidism?
- failure of target cell response to PTH
- genetic cause
What are the signs of psuedohypoparathyroidism?
- Short metacarpals
- Round face
- Short stature
- Calcified basal ganglia
- Low IQ
What do tests show for psudeoparathyroidism?
- Low calcium
- High PTH
- High or normal ALP
How do you treat psuedohypoparathyroidism?
same as primary hypothyroidism
What is pseudopseudohypoparathyroidism?
- morphological features of pseudohypoparathyroidism with normal biochem
- cause is genetic
What are RF for hypoparathyroidism?
- Thyroid surgery, Parathyroid surgery
- Chronic alcoholism
- Hypomagensaemia
- Moderate and chronic maternal hypercalcaemia (neonatal hypocalcaemia)
- Autosomal dominant conditions (e.g. mutations in CASR, GATA3)
- Hereditary haemochromatosis
- Transfusional iron overload in thalassaemia
- Metastatic cancer
What are symptoms of hypoparathyroidism?
- Muscle twitches, spasms and cramps: due to hypocalcaemia!
- Paraesthesia, numbness, tingling
- Poor memory, slowed thinking
- Convulsions
- Anxiety
- Dry hair, brittle nails
- Cataracts
What are signs of hypoparathyroidism?
- Chvostek’ sign
- Trousseau sign
- Irregular heart beat, tachycardia
- Laryngeal spasm (uncommon)
What are possible differential diagnosis of hypoparathyroidism?
- Hypovitaminosis D
- Hypomagnesaemia
- Hypoalbuminemia
- Pseudohypoparathyroidism
- Renal failure, chronic kidney disease
What are possible complications of hypoparathyroidism?
- Ectopic calcifications
- Cataract
- Hypercalcaemia
- Renal insufficiency
- Renal stones
What investigations do you do for hypoparathyroidism?
- Serum calcium
- Phosphate
- ALP
- serum albumi
- ECG: prolonged QT interval
- plasma intact PTH
- serum magnesium
- serum 25-hydroxyvitamin D
- serum phosphorus
- serum creatinine
What is serum calcium like in hypoparathyroidism?
low
What are phosphate levels like in hypoparathyroidism?
high
What are ALP levels in hypoparathyroidism?
normal
What are serum albumin levels like in hypoparathyroidism?
normal, a low albumin will give falsely low total serum calcium
What does an ECG show in hypoparathyroidism?
Prolonged QT interval
What is serum intact PTH level like in hypoparathyroidism?
low or normal
What is serum magnesium like in hypoparathyroidism?
low
What would serum 25-hydroxyvitamin D be like in hypoparathyroidism?
low
What would serum phosphorus be like in hypoparathyroidism?
usually elevated
What is the treatment for hypoparathyroidism?
Ca2+ supplements (calcium carbonate) + calcitrol
What is the treatment for hypoparathyroidism if severe?
- IV calcium
- With hypomagnesaemia: magnesium sulfate 1g IV every 6 hours
