Nephrology

CKD · AKI · Electrolytes · Renal Drug Dosing

CKD

Staging & Management

KDIGO CKD Definition

Abnormalities of kidney structure or function present for >3 months, with implications for health. Diagnosed by eGFR and/or ACR (albuminuria) — both should be measured at least twice over 90 days before labelling CKD.

GFR Categories — Click for Management

Albuminuria Categories (Urine ACR)

A1
< 3 mg/mmol
Normal to mildly increased
A2
3–30 mg/mmol
Moderately increased
A3
> 30 mg/mmol
Severely increased

The KDIGO heat map combines G + A categories: e.g. G3b A3 = very high risk of progression → nephrology referral.

Key GP Actions in CKD

ACEi/ARB first-line

In CKD with ACR ≥3 mg/mmol or diabetes. Reduces progression by ~30%. Check K+ and creatinine at 1–2 weeks (K+ rise <0.5 mmol/L and creatinine rise <25% acceptable).

SGLT2 inhibitors

Dapagliflozin / empagliflozin: KDIGO 2022 recommends in T2DM + CKD (eGFR 20–75). Reduces CV events and kidney failure by ~39% (DAPA-CKD trial). Do NOT start if eGFR <20.

Blood pressure

Target <130/80 mmHg (KDIGO 2021) in all CKD. Systolic target intensification if proteinuria. ACEi/ARB preferred if proteinuria. Avoid thiazides if eGFR <30.

Metformin

Continue if eGFR >45. Reduce dose if eGFR 30–45. STOP if eGFR <30 (risk of lactic acidosis). Hold at contrast/surgery/illness.

Anaemia

Target Hb 100–120 g/L in CKD. Diagnose cause first — iron deficiency common. IV iron if TSAT <20% + ferritin <100. ESA (EPO) if still low after iron optimisation — refer nephrology.

Mineral bone disease

CKD-MBD: elevated PTH + phosphate, low calcium + vitamin D. Treat: restrict dietary phosphate, phosphate binders, active vitamin D (calcitriol) in G4–5. Avoid prolonged hypercalcaemia.

Nephrology Referral Criteria

eGFR < 30 ml/min/1.73m² (G4–5)
Rapid decline: >25% drop in eGFR or >5 ml/min/yr
Urine ACR > 70 mg/mmol
Haematuria + proteinuria (possible GN)
Uncontrolled hypertension despite 3 drugs
Suspected renovascular disease
Recurrent AKI episodes
Planning RRT (HD/PD/transplant)