Is there one blood test that tests for everything?

Is there one blood test that tests for everything?

No, there is no single blood test that checks for everything.

But these 5 blood tests (well, each is really a group of tests) are a good start. They are the ‘basic bloods’ that many doctors request at the start of an illness, especially when it is not clear what is going on.

1. FBC (full blood count)

• Haemoglobin (‘Hb’)
  • 130-170 g/L for men
  • 110-150 g/L for women
  • The Hb reflects the number of red cells (which carry oxygen) in the blood – a higher number means more red cells. A low haemoglobin is called anaemia. A high haemoglobin is called polycythaemia
• White cell count (WC) = 4-11 x10^9/L (million per litre). These cells fight infection (and cancer and foreign bodies inside you)
• Platelet count = 150-400 x10^9/L (million per litre). These cells clot the blood.

2. U+E (urea and electrolytes) – assesses kidney function, mineral levels and acid/alkali balance

• Sodium (Na) = 135-145 mmol/L. A sodium <125 or >150 requires treatment today. Low or high can affect the function of the brain. If very low or high, the patient can become drowsy or even unconscious
• Potassium (K) = 3.5-5.3 mmol/L. A potassium <3.0 or >6.0 requires treatment today. Low or high can affect the function of the heart (and even stop)
• Chloride (Cl) = 95-105 mmol/L
• Bicarbonate (Bic) = 22-28 mmol/L (venous). Low indicates high acid/low alkali levels (acidosis), high indicates low acid/high alkali levels (alkalosis)
• Urea (U) = 3-7 mmol/L. High in CKD or AKI. If >50, you need a reason not to have dialysis
• Creatinine (Creat) = 60-120 μmol/L. High in CKD or AKI. If >500, you need a reason not to have dialysis
• eGFR = 90-120 ml/min/1.73m². Low in CKD – how your CKD stage is calculated.

3. Glucose (‘gluc’) and HbA1c

• Normal blood glucose = 4-6 mmol/L – and less than 8 mmol/L, two hours after a meal
  • Prediabetes is diagnosed if your random blood glucose = 7-11 mmol/L
  • Diabetes is diagnosed if you have a random blood glucose > 11 mmol/L (or a fasting blood glucose > 7 mmol/L)
• Normal HbA1c = 20-42 mmol/mol (or 4-6%)
  • Prediabetes is diagnosed if your HbA1c = 42-47 mmol/mol (6-6.5%)
  • Diabetes is diagnosed if your HbA1c > 47 mmol/mol or over (>6.5%).

4. Bone biochemistry (‘bone’)

• Calcium (Ca) = 2.2-2.6 mmol/L – below 1.8 or above 3.0 needs treatment; below 1.4 or above 3.5 needs treatment today. It is the primary mineral in bones and is crucial for bone health. About 99% of your body’s calcium is in your bones and teeth. The other 1% of it is in your blood
• Phosphate (PO4) = 0.8-1.4 mmol/L – also essential for bone structure and works in conjunction with calcium
• Alkaline phosphatase (alk phos, ALP) = 30-130 U/L – an enzyme that indicates bone formation activity, with elevated levels potentially signifying increased bone turnover
• Magnesium (Mg) = 0.7–1.0 mmol/L
• Parathyroid hormone (PTH) <5 pcmol/L – a hormone that is made by the 4 parathyroid glands (at the back of the thyroid gland in the neck). It controls calcium and phosphate levels in the bones and blood
• Vitamin D (vit D) >50 nmol/L – works with PTH.

5. Liver function tests (‘LFTs’) – also called liver enzymes

• Bilirubin (bili) = <21 µmol/L. High in liver disease
• Alkaline phosphatase (alk phos, ALP) = 30-130 IU/L. There are bone and liver subtypes of alk phos
• ɣ–glutamyl transpedtidase (GGT) = 1-55 IU/L
• Alanine aminotransferase (ALT) = 15-45 IU/L
• Aspartate aminotransferase (AST) = 15-42 IU/L
• Albumin (Alb) = 35-50 g/L. Low in liver disease
• Globulin (Glob) = 20-40 g/L
• Total protein (TP) = 60-80 g/L.

Bonus blood test

Summary

We have answered the question, is there one blood test that tests for everything? No, there is not. But the 5 blood tests (well, each is really a group of tests) above are a good start.