Endo Flashcards
Causes of diabetes insipidus
Cranial (no ADH secretion) - pituitary tumour - infection (meningitis) - sarcoidosis Nephrogenic (insensitive to ADH) - increased Ca2+ - decreased K+ - lithium - inherited AVPV2 gene - idiopathic
Sx of DI
Polyuria (UO > 3L), nocturia, polydipsia, sx of hypernatraemia (lethargy, irritability, confusion)
Ix for DI
U&Es, HbA1c (exclude DM), water deprivation test (diagnostic)
Water deprivation test results for
a) normal
b) cranial
c) nephrogenic
a) ADH secretion occurs so increased plasma osmolality urine concentration
b) decreased urine osmolality [dilute]
c) decreased urine osmolality [dilute]
=> desmopression administered
b) urine osmolality increase >50%
c) urine osmolality increase <45%
Mx for DI
TREAT CAUSE
Cranial => intranasal desmopressin
Nephrogenic => thiazide diuretic or NSAIDs (inhibit prostalgandin synthase as prostaglandin inhibits ADH)
TIDM summary card
Hyperglycaemia due to deficiency of insulin production as a result of AI destruction of beta cells (90% cases)
PC: polyuria + polydipsia, tired, wt loss, DKA (N&V, abdo pain, Kussmaul breathing)
Associated w/ HLADR3/4 + other AI conditions
Tx: insulin, pt education, DKA (1st line - fluids)
TIIDM summary card
Hyperglycaemia due to increased peripheral resistance to insulin action
PC: polyuria and polydipsia
RFs: obesity, FHx, ethnicity, drugs
Tx: 1st - diet and lifestyle, 2nd - metformin => sulphonylurea => insulin
Which blood glucose measurements are diagnostic of diabetes mellitus?
Fasting blood glucose >/= 7mmol/L
Random blood glucose >/= 11.1mmol/L
How may hypernatraemia present and how is it treated?
Rarer sodium imbalance
- lethargy, signs of dehydration, irritability, fits, confusion, coma
Replace water + treat cause
What causes hypernatraemia?
D&V
Diabetes insipidus
Primary hyperaldosteronism
What leads to hyponatraemia?
SIADH
What causes hyponatraemia?
Causes can be split based on water status of the pt
1) Dry (hypovolaemic)
- D&V, diuretics
2) Normal (euvolaemic)
- hypothyroidism, hypoadrenalism, SIADH causes
3) Wet (hypervolaemic)
- HF, cirrhosis, nephrotic syndrome
How may hyponatraemia present?
Presentations suggest water status of pt:
1) Dry => dry mucous membranes, tachycardia
2) Normal => other sx of endo cause
3) Wet => increased JVP
Potential ix after bloods show hyponatraemia
TFTs, short synACHTen test
CXR, breast exam, brain MRI (SIADH malignancies)
Possible causes of SIADHq
CNS pathology
Lung pathology
Drugs: SSRI, TCA, opiates, PPIs, carbamazepine
Tumours (don’t forget breast!)