These are the blood, urine and x-ray tests that should be done for most patients with mores severe AKI.
Blood tests
Full blood count (FBC)
- Haemoglobin (Hb; red cells). The normal range of Hb = 130-170 g/L (men), 110-150 g/L (women). A low Hb (called anaemia) is a feature of more severe AKI.
- White cells (4-11) (normal)
- Platelets (150-400) (normal)
CRP (infection)
Blood cultures – infection (sepsis)
U&E:
- sodium = 135-145 mmol/L (variable in AKI)
- potassium = 3.5-5.3 mmol/L) (may be high in AKI)
- urea = 3-7 mmol/L (high)
- creatinine = 60-120 mcmol/L (high)
Glucose (diabetes) = 4-6 mmol/L (normal)
Bicarbonate (acid levels) = 22-28 mmol/L (low)
Liver function tests (LFTs) (liver function) (normal)
Calcium (bone health) = 2.2-2.6 mmol/L (normal)
Phosphate (bones) = 0.8-1.4 mmol/L (normal or high)
Alkaline phosphatase (bones) = 50-150 iu/L (normal)
Parathyroid hormone (PTH) (bones) = <5 pcmol/L (normal)
Vitamin D (bones) (low)
Cholesterol (non-fasting) (normal)
‘Renal screen’ – this is only indicated for more severe AKI cases or where the diagnosis is not clear
Clotting (+/- blood film) – DIC, HUS/TTP
Creatine kinase (CK) – rhabdomyolysis
Anti-nuclear antibody (ANA) – positive in Systemic Lupus Erythematosus (SLE, lupus)
Anti-neutrophil cytoplasmic antibody (ANCA; with PR3 and MPO) – positive in vasculitis
Anti-glomerular basement membrane (anti-GBM) antibody – positive in Goodpasture’s Disease
Complement C3/4 – low in SLE
Double-stranded DNA (DsDNA) – positive in SLE
Serum electrophoresis – looking for an abnormal protein suggestive of myeloma (and other blood disorders)(negative)
Immunoglobulins (IgG, A and M) – e.g. IgA high in IgA nephropathy
Serum free light chains (SFL) – myeloma (and other blood disorders)
Hep B/C, HIV – viral associated GNs (membranous GN with Hep B, mesangiocapillary GN with Hep C, FSGS with HIV)
+/- Other blood tests:
Eosinophilia – acute interstitial nephritis
Antistreptolysin O (ASO) titre – post-infectious GN
Angiotensin converting enzyme (ACE) – sarcoidosis
Cryoglobulins – mesangiocapillary GN)
LDH/haptoglobin – high/low; HUS/TTP
Prostate specific antigen (PSA; in a man) – prostate cancer.
Urine tests
uACR (protein level in urine) = < 3 mg/mmol. If high (>100) may contribute to decision on need for a kidney biopsy (see below)
Mid-stream urine (MSU) – infection in urine
Imaging (x-rays etc)
CXR – pulmonary oedema and/or haemorrhage (vasculitis)
Renal ultrasound – number (2) and size (10-14 cm long) of kidneys, and cause of CKD.
Kidney biopsy
A small number of patients need a kidney (renal) biopsy. This is a procedure to take a sample of kidney tissue, about the size of a small pin, which is examined under the microscope. More information on MyHSN about them here.
Last Reviewed on 3 October 2023