Diabetes Cases Flashcards
What is the equation for osmolality?
Osmolality = 2 (Na + K) + Urea + Glucose
Why do we have the term anion gap?
Cations (Na, K) = Anions (Cl, bicarb, others)
Others = anion gap, anions not measured
How do you calculate the anion gap?
Anion gap = Na + K - Cl - Bicarb
What is suggested by a high anion gap?
Extra anions e.g. Ketones, Anti-freeze
What could cause a respiratory alkalosis and unconsciousness in a known diabetic?
Hypoglycaemia causing anxiety
Anxiety causing hyperventilation
A 60M presents unconscious with a history of polyuria and polydipsia.
Glucose: 60
Osmolality: 442
pH: 7.30
Why is he unconscious? What is the diagnosis?
Severe dehydration
Hyperglycaemic hyperosmolar state (HHS)
Presents in those with longstanding undiagnosed DM. High glucose, not drinking enough, peeing a lot, become dehydrated
A 59M with known T2DM on a good diet and metformin presents unconscious.
Urine: -ve for ketones
Glucose: 4
Bicarb: 4
CO2: 1.3
pH: 7.1
Anion gap: 50
Why is he unconscious?
Brain can’t function at such an acidic pH
When ketones are normal, what can cause an excess of anions?
Methanol
Ethanol
Lactate
Metformin OD can cause lactic acidosis
How does metformin cause a lactic acidosis in overdose?
Metformin inhibits the conversion of lactate to glucose in the liver
What measurements define type 2 diabetes?
Fasting glucose >7.0 mM
Glucose tolerance test (75g glucose given at time 0): plasma glucose >11.1 mM at 2h
What is compensation in relation to acid-base balance?
Improving the pH at the expense of worsening the CO2 derangement
In which conditions do we see compensation?
DKA:
ketones acidic, respiratory compensation, over breathe, blow off CO2. pH increases, CO2 further decreases
COPD:
Less breathing (chronically), over time kidneys try to increase pH + reduce acid, so CO2 further increases
