Which Tests to Get Based on Your Symptoms: A Simple Guide
"Get some tests done" — easy advice to give, hard to act on without specifics. Especially when the symptom is vague: fatigue, headaches, stomach discomfort. Where do you even start? This guide helps you understand which lab tests to prioritise based on your symptoms — before a doctor's appointment, or while you're waiting for one.
Fatigue and weakness without a clear cause — what to check
Constant tiredness that doesn't improve with sleep, struggling to get through a normal day — this isn't "just stress." It's a symptom with identifiable causes, most of which are picked up by routine blood tests.
Starting panel for chronic fatigue:
- Full blood count (FBC) with differential — identifies anaemia, hidden infections, inflammation.
- TSH (thyroid-stimulating hormone) — hypothyroidism is one of the most common causes of persistent fatigue, especially in women.
- Ferritin and serum iron — iron deficiency causes fatigue even without full-blown anaemia.
- Vitamin D — deficiency is widespread in low-sunlight regions and causes fatigue, muscle weakness, and low mood.
- Vitamin B12 — especially relevant for vegetarians and people over 50.
- Fasting blood glucose — to rule out a blood sugar disorder.
Frequent headaches — what to check
Blood tests for headaches don't directly find the cause (migraines aren't visible in blood), but they rule out conditions that mimic headache.
- Full blood count — anaemia can cause persistent headaches.
- Blood pressure — measure it several times at different times of day. Hypertension is a common headache trigger.
- Blood glucose — hypoglycaemia (low blood sugar) causes headaches.
- TSH — both over- and underactive thyroid can produce headaches.
- Urinalysis — if an infectious cause is suspected.
If headaches are severe, frequent, and don't respond to usual painkillers — you need a neurology consultation and possibly a brain MRI.
Abdominal pain — the starting panel
For stomach pain, tests are aimed at detecting inflammation, infection, or organ dysfunction.
- Full blood count — elevated white cells indicate inflammation or infection.
- CRP (C-reactive protein) — inflammation marker; rises with gastritis, pancreatitis, gut infections.
- Liver function: ALT, AST, bilirubin, GGT — liver and gallbladder status.
- Amylase and lipase — pancreatic function.
- Urinalysis — kidney stones and renal colic often mimic abdominal pain.
- Faecal occult blood — if an ulcer or inflammatory bowel disease is suspected.
Joint and back pain
Joint pain can be degenerative (osteoarthritis), inflammatory (arthritis, gout), or secondary to other conditions. Tests help identify the cause.
- FBC + CRP — is there an inflammatory process?
- Uric acid — gout. Especially relevant when the big toe is affected.
- Rheumatoid factor (RF) and anti-CCP antibodies — if rheumatoid arthritis is suspected.
- ANA (antinuclear antibodies) — screening for systemic autoimmune conditions.
- Vitamin D and calcium — deficiency directly affects bone and joint health.
Skin symptoms
Rashes, itching, scaling, acne — skin often reflects internal problems. Basic tests for skin symptoms:
- FBC with eosinophil count — elevated levels point to allergy or parasites.
- Total IgE — overall allergic load.
- Blood glucose — diabetes often presents with skin itching and poor wound healing.
- TSH — thyroid disorders cause dry skin and hair loss.
- Ferritin — iron deficiency causes dry skin and brittle nails.
Universal baseline check-up: what to get if nothing hurts but you want to check
If you're healthy but want a preventive check-up, here's a minimum panel for an adult — every 1–2 years:
- Full blood count with differential
- Metabolic panel: fasting glucose, total cholesterol, LDL, HDL, triglycerides, ALT, AST, creatinine, urea
- TSH
- Urinalysis
- Vitamin D
- Blood pressure (self-measured)
- ECG — annually after age 40
After 40, add: PSA (men), mammography (women), colonoscopy every 5–10 years, bone density scan (if osteoporosis risk is present).
To get a more personalised test list based on your specific symptoms, describe your situation to the assistant and it will put together a tailored panel.
Frequently asked questions
Do I need to fast before blood tests?
Fasting is required for: blood glucose, metabolic panel (cholesterol, triglycerides, bilirubin), and thyroid hormones. A full blood count and urinalysis can be done without fasting, though morning collection is traditionally recommended. Check the specific requirements with your lab before your appointment.
How often should a healthy person get blood tests?
A basic preventive check-up every 1–2 years is sufficient for adults under 40 without chronic conditions. After 40 — annually. For chronic conditions — as directed by your doctor, potentially more often.
Can I order blood tests without a doctor's referral?
Yes. Private laboratories allow you to order most tests directly. Keep in mind that interpreting results is best done with a doctor — a single out-of-range value doesn't always indicate disease.
What does "normal range" mean — and why does it vary?
Reference ranges on lab reports are statistical averages for a large population. Normal depends on age, sex, and the lab's measurement method. For example, a ferritin value that's "normal" for a 60-year-old man could be too high for a 30-year-old woman. Results should be interpreted by a doctor in clinical context.
Why do my tests come back normal but I still feel unwell?
Standard panels don't cover everything. Some conditions require specific tests — for example, coeliac disease needs anti-gliadin and anti-transglutaminase antibodies, not just a blood count. Sometimes the cause of feeling unwell is functional: stress, poor sleep, diet. Keep looking for answers with your doctor.
Should I include tumour markers in a routine check-up?
No — tumour markers are not useful for routine screening. Most (PSA being an exception) lack sufficient specificity: they can be elevated by inflammation (false alarm) or normal despite a real tumour. Cancer screening is done through age-specific methods: mammography, colonoscopy, skin checks by a dermatologist.
Symptomatica is an informational reference service. Not a medical service; does not diagnose or prescribe treatment. For any symptoms, please consult a doctor.