How we keep this safe
Detectives Health is a specialist-led laboratory education and results interpretation platform designed to help people better understand blood test results. It explains what blood tests measure and what values typically look like in healthy adults. It does not diagnose, rank disease risk, or replace your clinician.
What we deliberately do not do
- Diagnose any condition from one or more lab values.
- Estimate the probability that you have cancer, a heart attack or another disease.
- Prescribe, change or stop any medication.
- Replace a clinician's interpretation of your full history and examination.
The safety pipeline behind every result
Every result you enter passes through six deterministic steps before any educational text is shown:
- Step 1Result Entered
- Step 2Critical Value Check
- Step 3Urgent Safety Review
- Step 4Educational Interpretation
- Step 5Uncertainty Assessment
- Step 6Professional Advice Reminder
- You enter a value (Personal Lab mode only).
- A deterministic rule engine checks for critical / panic values.
- If critical → we hide the long explanation and show an "urgent review" message.
- If not critical → we show the typical reference range with safe wording.
- An uncertainty layer downgrades certainty when context is missing. Laboratory results should always be interpreted alongside age, sex, pregnancy status, symptoms, medications, previous results, and the reason the test was requested. Where important clinical information is unavailable, Detectives Health intentionally uses cautious wording.
- A second-opinion banner recommends a repeat test or clinician review for any out-of-range result.
Laboratory Interpretation Principles
As a specialist-led platform, Detectives Health interprets results the way a laboratory professional would — not as a simple "high or low" check. Every explanation is shaped by:
- Reference intervals — population-based typical ranges, adjusted for age and sex where possible.
- Analytical variation — the inherent imprecision of the laboratory method used.
- Biological variation — natural fluctuation within the same person over time.
- Pre-analytical factors — fasting, posture, time of day, tourniquet time, transport conditions.
- Sample quality — haemolysis, lipaemia, icterus and clotting can all affect a result.
- Clinical context — symptoms, medications and the reason the test was requested.
- Previous results when available — a trend is almost always more informative than a single number.
Why your result may be different next time
Many patients don't realise how much a single blood result can vary. Two samples taken from the same person on different days can legitimately give different numbers without any change in underlying health. Common reasons include:
- Hydration status at the time of the sample
- Time of day the sample was taken
- Recent exercise
- Recent meals or fasting state
- Medication, including supplements and over-the-counter drugs
- Recent or current infection
- Natural biological variation within the same individual
- Analytical variation between laboratory methods and analysers
This is why a single abnormal value rarely justifies alarm, and why clinicians often repeat a test before acting on it.
Who reviews the content
Educational content on Detectives Health is reviewed by a qualified laboratory professional or healthcare reviewer, depending on the service selected. This keeps the reviewer description consistent with the laboratory-led nature of the platform and avoids any confusion about who performs the review.
Critical-value thresholds we currently watch
The educational thresholds used by Detectives Health are informed by commonly used UK laboratory practice and published professional guidance. Individual laboratories may use different validated alert values.
| Test | Critical band | Why |
|---|---|---|
| haemoglobin | ≤ 70 g/L · ≥ 200 g/L | Severe anaemia or marked erythrocytosis can need same-day assessment. |
| platelets | ≤ 50 ×10⁹/L · ≥ 1000 ×10⁹/L | Very low platelets raise bleeding risk; very high raises clotting risk. |
| wbc | ≤ 2 ×10⁹/L · ≥ 30 ×10⁹/L | Marked changes can indicate serious infection or haematological disease. |
| neutrophils | ≤ 1 ×10⁹/L · ≥ 20 ×10⁹/L | Neutropenia below 1.0 is a sepsis risk requiring urgent review. |
| sodium | ≤ 120 mmol/L · ≥ 155 mmol/L | Severe sodium derangement can affect brain function. |
| potassium | ≤ 2.8 mmol/L · ≥ 6 mmol/L | Potassium outside this band can trigger cardiac arrhythmia. |
| calcium | ≤ 1.8 mmol/L · ≥ 3 mmol/L | Severe calcium changes affect heart and nervous system. |
| glucose-fasting | ≤ 2.5 mmol/L · ≥ 25 mmol/L | Hypoglycaemia or hyperglycaemic crisis needs urgent care. |
| troponin | ≥ 0.04 µg/L | Any rise above the assay cut-off can indicate cardiac injury. |
| crp | ≥ 100 mg/L | Marked rise is associated with significant infection or inflammation. |
| ddimer | ≥ 1 mg/L | Significant elevation needs clinical assessment for clotting events. |
| inr | ≥ 5 ratio | INR above 5 carries a high bleeding risk. |
| bnp | ≥ 400 pg/mL | Marked elevation can indicate heart failure decompensation. |
| psa | ≥ 20 ng/mL | Levels in this band trigger urgent urology referral pathways in NHS guidance. |
Education vs Personal Lab mode
By default the app is in Education mode: you can read about every test, no personal data is interpreted. Switching to Personal Lab unlocks the result input, the tracker, and the uncertainty-aware feedback — and asks you to acknowledge that the output is not a diagnosis.
When to seek urgent help
Regardless of any number on a screen — trust your symptoms. New chest pain, breathlessness, sudden weakness, confusion, severe bleeding, or feeling acutely unwell are clinical emergencies. In the UK, call 999 for emergencies or 111 for urgent advice.
If you have been contacted directly by the laboratory or your healthcare provider regarding a critical result, follow their advice immediately. Do not wait for further information from an educational platform before acting on instructions from your clinical team.