Chemical Pathology 12 - Meeran's Diabetes CPC (pituitary) Flashcards
What are the 3 biochemical definitions of diabetes?
Fasting PLASMA glucose >7.0mM (nb. this value does not apply to fingerprick whole blood test)
HbA1c > 6.5% (equivalent >48mmol/mol)
2 hour plasma glucose in Glucose Tolerance Test of >11.1mM
What HbA1c values count as ‘impaired glucose tolerance’?
42-48mmol/mol
Recall 3 differentials for metabolic alkalosis
H+ loss via vomiting (see history)
Hypokalaemia
Bicarb ingestion (rennies)
What is the calculation for osmolality?
2(Na + K) + Urea + Glucose
What is the calculation for anion gap?
Na + K - Cl - HCO3
How can anion gap assist in diagnosis of DKA?
Ketones are anions
Therefore, in DKA anion gap will be large
How can pituitary-dependent Cushing’s and ectopic ACTH be distinguished?
Pituitary petrosal sinus sampling
If a patient has a high ACTH and very severe hypokalaemia, what is the most likely cause of the high ACTH?
Ectopic ACTH
What test is best to diagnose the cause of ectopic ACTH?
CXR
How can acute and chronic renal failure be distinguished?
Renal biopsy
How should acute tubular necrosis be managed?
Dialyse for 3 weeks and they willl recover
How should diabetic glomerular kidney disease be managed?
This is a lifelong condition that will require lifelong dialysis
What is the difference in expected pCO2 in uncompensated metabolic and respiratory acidosis?
Metabolic: low pCO2 (equilibrium pushed right to produce more CO2 but this is breathed off nicely)
Respiratory: high pCO2 (not ventilating properly to get rid of CO2)
What is the difference in expected pCO2 in uncompensated metabolic and respiratory alkalosis?
Metabolic: high pCO2 (reduced H+ means resp rate decreases to produce more CO2 to replace H+)
Respiratory: low pCO2 (hyperventilation –> blowing off all CO2)
How can hypoglycaemia lead to a respiratory alkalosis?
Can cause significant anxiety –> hyperventilation
