Lab Case 99 – Interpretation

A 66 year old female with chronic renal failure presents feeling unwell for a day. 

Describe and Interpret:

pH severe acidaemia, HCO3  severe metabolic acidosis, AG = 28 – very high, delta ratio 1.2 (pure HAGMA)

so severe HAGMA

Compensation: expected CO2 = 23, actual = 39

mixed HAGMA and respiratory acidosis

A-a gradient = (760-47)FiO2 – 1.25XpCO2 -pO2, assume Fi)2 of 60% on 10 litres

A-a gradient very high implying VQ mismatch or shunt

Other relevant bloods: very high Creatinine in keeping with CRF (check baseline), normal K (whole body depletion, based on pH, expected K 2 mmol/l), lactate, glucose



Renal – acute on chronic

Drugs – paracetamol, codeine, metformin, salicylates (nothing in history to suggest), cause of renal failure (RTA from NSAID abuse)

Check ketones

Central cause – uraemia, infection, CVA

Focus of assessment

Signs of acute fluid overload

Causes of shock – obstructive (pericardial effusion/ tamponade, PE), hypovolaemic, septic

Sources of sepsis

Neuro exam

signs of drug use

Indications of urgent dialysis:

intractable acidosis

Severe electrolyte derangement

Fluid overload

Drugs, toxins

Severe uraemia – severe nausea, seizure, pericarditis, bleeding