Lesson 2: Chemistry, Endocrine and Metabolic Testing

Electrolytes, renal and liver panels, glucose, thyroid and hormone testing.

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Complete learning materials

Review each topic, apply the clinical case, then complete the linked ten-question assessment.

Electrolyte interpretation

  • Inspect sodium, potassium, chloride, bicarbonate and renal function together. Hyperkalemia with ECG changes or marked severity needs immediate emergency management.
  • Consider hemolysis in a surprising isolated potassium elevation; repeat promptly when appropriate without delaying urgent care if symptomatic or high risk.
  • Corrected interpretation of sodium may be affected by glucose; interpret osmolality, volume status and medication history.

Renal and hepatic panels

  • Creatinine and eGFR reflect filtration estimates and can be affected by muscle mass and acute changes; eGFR formulas are less reliable during rapidly changing kidney function.
  • Urine albumin-to-creatinine ratio helps assess kidney damage; confirm persistent albuminuria because exercise, infection and other factors may transiently raise it.
  • Interpret ALT, AST, ALP, bilirubin and albumin in hepatocellular vs cholestatic patterns; check clinical severity and synthetic function when indicated.

Glycemic and thyroid investigations

  • Use guideline-appropriate fasting plasma glucose, A1c or oral glucose testing for diabetes diagnosis; A1c can mislead in hemolysis, anemia or altered RBC turnover.
  • TSH with reflex free T4 is commonly useful in thyroid evaluation; biotin and medication interference can produce misleading immunoassay results.
  • Use targeted hormonal tests based on symptoms and pretest probability rather than broad unindicated panels.

Acid-base and specimen factors

  • Interpret acid-base disturbances with clinical status, bicarbonate, anion gap and blood gas when indicated; respiratory failure and significant acidosis need urgent assessment.
  • Review sample timing, fasting requirements, anticoagulant tubes, posture and drugs before interpreting unusual findings.
  • Explain incidental minor abnormalities, decide when repeat testing is needed and establish ownership for follow-up.

Applied clinical case

Case: An asymptomatic patient has potassium 6.4 mmol/L reported from a hemolyzed specimen. Check urgency, medication and renal context, promptly repeat an appropriate sample and obtain urgent ECG/emergency evaluation when indicated.

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