Biochemistry of Endocrine Disorders Flashcards
What are the two main variants of diabetes insipidus?
- Cranial
- Nephrogenic
What are the main causes of nephrogenic diabetes insipidus?
- Acquired
- Inherited
- Chronic renal failure
- Lithium
What are the two key causes of acquired diabetes insipidus?
- Hypokalaemia
- Hypercalcaemia
In nephrogenic diabetes insipidus, what causes the condition?
Failure of the kidneys to respond to ADH
What is the general cause behind all types of cranial diabetes insipidus?
There is a failure of ADH production
What are the main causes of cranial diabetes insipidus?
- Tumour
- Trauma
- Granulomatous disease
How is serum osmolality calculated?
2(Na+ + K+) + Glucose + Urea
Which condition which may induce cranial diabetes insipidus is associated with acute onset?
Apoplexy
What is apoplexy?
Unconsciousness or incapacity resulting from a cerebral haemorrhage or stroke
How can diabetes insipidus be diagnosed?
Water deprivation test
Urine osmolarity is monitored when fluids are deprived
Urine fails to concentrate in DI
How can nephrogenic DI be differentiated from cranial DI?
Administer desmopressin (DDAVP)
- Cranial DI - Urine will concentrate in water deprivation
- Nephrogenic DI - Urine will fail to concentrate (kindneys are unresponsive to ADH or analogues)
In a patient with suspected panhypopituitarism, which clinical test is essential and what does it establish?
Visual field examination
Any development of bitemporal hemianopia
(due to compression of tumour on optic chiasm)
What is Addison’s disease?
Primary autoimmune adrenal insufficiency
Addison’s disease can result in deficiency of which hormone types?
- Glucocorticoids
- Mineralocorticoids
- Androgens
Why is the impactation on androgen production in Addison’s disease worse for women than it is for men?
In men adrenal androgens are fairly insignificant
The vast majority of androgens (such as testosterone) are made in the testes