Parathyroid and Ions Flashcards
Role of parathyroid hormone (PTH)
Bone resorption
Increase Ca reabsorption in kidney
Decrease PO4 reabsorption in kidney
Stimulates vit D
Role of vit D
Increase Ca and PO4 absorption in gut
Increase Ca and PO4 reabsorption in kidney
Bone turnover
Role of calcitonin
Reduces Ca and PO4
Absorbed into bone
Site of calcitonin release
C cells of thyroid
Effect of Mg on Ca
Low Mg inhibits PTH release
May cause hypocalcaemia
Features of hyercalcaemia
Bones, stones, abdo groans and psychic moans
Bone pain, #s
Renal stones
Abdo pain, constipation, N/V
Confusion, weakness
Mx of acute hypercalcaemia
Rehydrate
Bisphosphonate
Treat cause
Features of hypocalcaemia
Cramps
Spasms
Neuromuscular excitability
Trousseau’s sign
Chvostek’s sign
Trousseau’s sign
Inflate BP cuff
Wrist and fingers flex
Chvostek’s sign
Tap facial nerve over parotid
Corner of mouth twitches
Sx of severe hypophosphataemia
Muscle weakness
Rhabdomyolysis
RC, WC, PLT dysfunction
Arrhythmias
Sx of hypomagnesaemia
Paraesthesia
Ataxia
Seizures
Tetany
Arrhythmias
Sx of severe hypermagnesaemia
Neuromuscular depression
Low BP
Bradycardia
Respiratory depression
Coma
Sx of zinc deficiency
Alopecia
Dermatitis
Night blindness
Diarrhoae
Causes of primary hyperparathyroidism
Solitary adenoma ~80%
Hyperplasia
Ix for primary hyperparathyroidism
High Ca
High PTH
Low PO4
Mx of hyperparathyroidism
Fluid intake to prevent renal stones
Avoid thiazides
Excision of adenoma
Indications for excision of parathyroid adenoma
High Ca
Osteoporosis
Renal stones
Reduced renal function
Age < 50 yrs
Multiple Endocrine Neoplasia (MEN) inheritance
Autosomal dominant
MEN 1
Parathyroid adenoma
Pancreas tumour
Pituitary prolactinoma
MEN 2a
Parathyroid tumour
Medullary Thyroid cancer
Phaeochromocytoma
MEN 1 gene
Tumour suppressor gene
MEN 2b
Medullary thyroid cancer
Phaechromocytoma
Mucosal neuromas
Marfanoid features
MEN 2a and b gene
ret proto-oncogene
Receptor tyrosine kinase
Definition of secondary hyperparathyroidism
Low Ca leads to increase in PTH
Causes of secondary hyperparathyroidism
Vit D deficiency
CKD
Rx of secondary hyperparathyroidism
Treat cause
Vit D
Tertiary hyperparathyroidism definition
Prolongued secondary hyperparathyroidism
Parathyroid glands become hyperplastic
High PTH despite high Ca
Causes of tertiary hyperparathyroidism
CKD
Definition of malignant hyperparathyroidism
Cancers produce PTHrP
(Parathyroid related protein)
Cancers causing malignant hyperparathyroidism
Squamous cell lung cancers
Breast
Renal cell carcinomas
Primary hypoparathyroidism definition
Gland failure
Low PTH
Ix for primary hypoparathyroidism
Low Ca
Low PTH
High PO4
Causes of primary hypoparathyroidism
Autoimmune
Congenital (DiGeorge)
Rx of primary hypoparathyroidism
Ca
Synthetic PTH
Causes of secondary hypoparathyroidism
Radiation
(Para) thyroidectomy
Hypomagnesaemia
Pseudohypoparathyroidism definition
Failure to respond to PTH
Signs of pseudohypoparathyroidism
Short metacarpals
Round face
Short stature
Low IQ
Calcified basal ganglia
Cause of pseudohypoparathyroidism
Genetic
Definition of pseudopseudohypoparathyroidism
Same as pseudohypoparathyroidism
But normal biochemistry
Genetic cause
Von Hippel-Lindau syndrome inheritance
Autosomal dominant
Von Hippel-Lindau syndrome mutation
Tumour suppressor gene
Von Hippel-Lindau syndrome features
Predisposes to bilateral renal cysts
Retinal haemangioblastoma
Cerebellar haemangioblastoma
Phaeochromocytoma
Risk of renal cysts in Von Hippel-Lindau syndrome
Risk of transformation to renal cell cancer
