Blood Results 🧪
Reference tables for interpreting blood results. Normal ranges, abnormal values, and clinical significance of common laboratory tests for NCHDs.
📋 Overview
- Blood results are a core part of patient assessment. Recognising abnormal values quickly and understanding likely causes is critical on-call.
- The tables below list common tests, their normal reference ranges, and possible causes for abnormal results.
Full Blood Count (FBC)
Essential haematology parameters
| Test | Normal Range | High Causes | Low Causes |
|---|---|---|---|
| Hb | 13-18 g/dL (M), 11.5–16.5 g/dL (F) | Dehydration, polycythaemia | Anaemia, bleeding, CKD |
| WCC | 4–11 ×10⁹/L | Infection, inflammation, leukaemia | Aplastic anaemia, chemotherapy, viral infection |
| Platelets | 150–400 ×10⁹/L | Inflammation, iron deficiency | ITP, DIC, sepsis |
Hb
13-18 g/dL (M), 11.5–16.5 g/dL (F)
Dehydration, polycythaemia
Anaemia, bleeding, CKD
WCC
4–11 ×10⁹/L
Infection, inflammation, leukaemia
Aplastic anaemia, chemotherapy, viral infection
Platelets
150–400 ×10⁹/L
Inflammation, iron deficiency
ITP, DIC, sepsis
Urea & Electrolytes (U&E)
Renal function and electrolyte balance
| Test | Normal Range | High Causes | Low Causes |
|---|---|---|---|
| Sodium (Na⁺) | 135–145 mmol/L | Dehydration, SIADH | Diuretics, Addison's, fluid overload |
| Potassium (K⁺) | 3.5–5.0 mmol/L | AKI, ACEi, haemolysis | Diuretics, GI loss, insulin |
| Urea | 2.5–7.8 mmol/L | Renal dysfunction, dehydration, GI bleed | Low protein intake, liver disease |
| Creatinine | 60–110 µmol/L | Renal failure, rhabdomyolysis | Low muscle mass |
Sodium (Na⁺)
135–145 mmol/L
Dehydration, SIADH
Diuretics, Addison's, fluid overload
Potassium (K⁺)
3.5–5.0 mmol/L
AKI, ACEi, haemolysis
Diuretics, GI loss, insulin
Urea
2.5–7.8 mmol/L
Renal dysfunction, dehydration, GI bleed
Low protein intake, liver disease
Creatinine
60–110 µmol/L
Renal failure, rhabdomyolysis
Low muscle mass
Liver Function Tests (LFTs)
Hepatic function assessment
| Test | Normal Range | High Causes | Low Causes |
|---|---|---|---|
| ALT | <40 IU/L | Hepatitis, alcohol, meds | Not usually significant |
| ALP | 30–130 IU/L | Cholestasis, bone disease | Malnutrition |
| Bilirubin | <20 µmol/L | Haemolysis, liver disease | Not usually significant |
| Albumin | 35–50 g/L | Dehydration | Liver disease, nephrotic syndrome |
ALT
<40 IU/L
Hepatitis, alcohol, meds
Not usually significant
ALP
30–130 IU/L
Cholestasis, bone disease
Malnutrition
Bilirubin
<20 µmol/L
Haemolysis, liver disease
Not usually significant
Albumin
35–50 g/L
Dehydration
Liver disease, nephrotic syndrome
TFT Interpretation Guide
Thyroid function test patterns
| Condition | TSH | Free T4 | Free T3 | Notes |
|---|---|---|---|---|
| Primary Hypothyroidism | ↑ | ↓ | ↓ or Normal | Thyroid gland failure |
| Subclinical Hypothyroidism | ↑ | Normal | Normal | Early thyroid failure |
| Primary Hyperthyroidism | ↓ | ↑ | ↑ | Graves', toxic nodules |
| Subclinical Hyperthyroidism | ↓ | Normal | Normal | Often early hyperthyroidism |
| Secondary Hypothyroidism | ↓ or Normal | ↓ | ↓ | Pituitary dysfunction |
| Sick Euthyroid | ↓ or Normal | ↓ | ↓ or Normal | Non-thyroidal illness |
Primary Hypothyroidism
↑
↓
↓ or Normal
Thyroid gland failure
Subclinical Hypothyroidism
↑
Normal
Normal
Early thyroid failure
Primary Hyperthyroidism
↓
↑
↑
Graves', toxic nodules
Subclinical Hyperthyroidism
↓
Normal
Normal
Often early hyperthyroidism
Secondary Hypothyroidism
↓ or Normal
↓
↓
Pituitary dysfunction
Sick Euthyroid
↓ or Normal
↓
↓ or Normal
Non-thyroidal illness
Tumour Markers
Oncological biomarkers and associations
| Marker | Associated Cancer(s) | Notes |
|---|---|---|
| AFP | Hepatocellular carcinoma, germ cell tumours | Also raised in liver disease |
| CEA | Colorectal, pancreatic, gastric, breast | Used for monitoring, not screening |
| CA 19-9 | Pancreatic, biliary tract cancers | May also rise in benign biliary disease |
| CA 15-3 | Breast cancer | Mainly for monitoring recurrence |
| CA 125 | Ovarian cancer | Also raised in benign conditions (e.g. endometriosis) |
| PSA | Prostate cancer | Screening and monitoring; consider age and DRE |
| Beta-hCG | Germ cell tumours, choriocarcinoma | Also used in pregnancy testing |
AFP
Hepatocellular carcinoma, germ cell tumours
Also raised in liver disease
CEA
Colorectal, pancreatic, gastric, breast
Used for monitoring, not screening
CA 19-9
Pancreatic, biliary tract cancers
May also rise in benign biliary disease
CA 15-3
Breast cancer
Mainly for monitoring recurrence
CA 125
Ovarian cancer
Also raised in benign conditions (e.g. endometriosis)
PSA
Prostate cancer
Screening and monitoring; consider age and DRE
Beta-hCG
Germ cell tumours, choriocarcinoma
Also used in pregnancy testing
Educational reference only. Medical disclaimer