BI11.1-2 | Organ Function tests and Hormones — Summary & Reflection

REFLECT

A 45-year-old diabetic patient presents to your PHC with gradual swelling of the legs and face for 3 months. You order both an RFT and a urine protein test. The RFT shows creatinine 2.8 mg/dL, BUN 42 mg/dL, eGFR 22 mL/min. Urine protein 3.8 g/day.

Describe step by step: (1) What stage of CKD is this? (2) What is the most likely cause? (3) What single additional test would most reliably confirm diabetic nephropathy? (4) What biochemical principle underlies the elevated creatinine?

KEY TAKEAWAYS

Liver Function Tests:
- ALT/AST elevation → hepatocellular injury (viral hepatitis, drugs)
- ALP/GGT elevation → cholestasis (bile duct obstruction)
- Albumin and PT → synthetic function (fall in chronic liver disease)
- Direct > indirect bilirubin = hepatocellular/cholestatic; indirect > direct = haemolysis or Gilbert's

Renal Function Tests:
- Creatinine = GFR surrogate (rises when GFR falls >50%)
- BUN:Creatinine >20 = pre-renal; 10–20 = renal/post-renal
- Massive proteinuria + hypoalbuminaemia = nephrotic syndrome
- Microalbuminuria = earliest marker of diabetic nephropathy

Thyroid Function Tests:
- TSH = best single screening test for thyroid disease
- High TSH + low fT4 = primary hypothyroidism (thyroid failure)
- Low TSH + high fT4/T3 = hyperthyroidism (Graves', toxic nodule)
- Low TSH + low fT4 = secondary hypothyroidism (pituitary disease)
- Anti-TPO+ = autoimmune (Hashimoto's or Graves')