FixFirst / Guides
Plain-English guides to understanding your lab results. What the numbers mean, what standard panels miss, and what to do about it — written for patients, not clinicians.
Symptom investigation
For when the tests say fine but you don't feel it — and for finding the tests your standard panel routinely skips.
Labs Normal, Still Tired? The Borderline Markers Standard Panels Miss
Six markers that sit in the "technically normal" zone but are clinically linked to fatigue, brain fog, and low energy — ferritin, Vitamin D, TSH, B12, magnesium, and fasting glucose — and where the borderline zone for each one starts.
Blood Tests for Fatigue: What to Ask For (and What Standard Panels Miss)
A thorough fatigue workup covers 4 cause clusters: iron status, thyroid function, blood sugar, and nutrients. Here are the specific tests in each cluster, why doctors often skip them, and a script for requesting them.
Blood Tests for Brain Fog: Which Markers to Check
The overlap between brain fog and fatigue is real — but the markers differ. Homocysteine, thyroid antibodies, fasting insulin, and B12 active fraction are the ones most likely missed on a standard workup.
Already have your results?
Upload your report and see what needs attention
FixFirst checks 40+ biomarkers against clinical guidelines, flags borderline values standard ranges miss, and ranks your top 3 priorities — 45 seconds, free, no account.
Panel walkthroughs
Panel-by-panel guides to what each number means, what the reference ranges miss, and which values are worth watching closely.
How to Read Blood Test Results: A Complete Guide
What reference ranges actually represent, why two people can have the same value and different levels of risk, and the difference between "in range" and "optimal" — the concept behind everything else in this library.
How to Read a CBC (Complete Blood Count)
The most commonly ordered panel — but haemoglobin, MCV, RDW, and white cell differentials each tell a different story. What each value signals, and where the borderline zones start before anaemia is flagged.
How to Read a Lipid Panel
LDL, HDL, triglycerides, and total cholesterol — what each number means on its own and why the ratio between them matters more than any single value. Plus what "high LDL" actually requires context to interpret.
How to Read a Comprehensive Metabolic Panel (CMP)
Kidney markers (creatinine, eGFR), liver enzymes (ALT, AST), electrolytes, and blood glucose — what each cluster is screening for and the values that warrant a closer look.
How to Read a Thyroid Panel (TSH, Free T3, Free T4)
Why TSH alone misses subclinical thyroid dysfunction, what Free T3 and Free T4 add that TSH can't show, and the values associated with persistent fatigue even when TSH prints as "normal."
Deep dives
Individual guides to the markers that come up most often — what a high or low result means, what the borderline zone looks like, and what to do about it.
What Does Low Ferritin Mean? Symptoms, Causes, and What to Do
Ferritin is the most commonly missed marker on a standard panel. It can be depleted for months before haemoglobin drops — meaning a normal CBC doesn't rule it out. Here's what low ferritin looks like and how to address it.
Low Vitamin D: Symptoms, What the Range Means, and How to Fix It
The NIH flags insufficiency at 20–29 ng/mL. Most labs only flag deficiency below 20. That gap — where millions of results land — is where fatigue, low mood, and immune suppression commonly show up.
High LDL Cholesterol: What It Means and When to Act
LDL above the reference range is not always the same risk. Context — your HDL ratio, triglycerides, family history, and whether you're on a low-carb diet — changes the picture significantly.
Low B12: The Borderline Zone Most Doctors Miss
NICE identifies a neurological risk zone at 140–220 pg/mL — below the standard flag threshold. B12 deficiency symptoms can appear well before the lab result triggers a clinical alert.
TSH Levels Explained: What's Normal vs. What's Optimal
The ATA range goes up to 4.0–4.5 mIU/L. Many patients with fatigue and cold intolerance don't feel well above 2.5. The guide covers what TSH is measuring, where the evidence-based optimal zone sits, and when to request Free T3.
What Does High HbA1c Mean? (And What to Do About It)
HbA1c is a 3-month average of blood sugar control. The ADA prediabetes range starts at 5.7%. Here's what different values signal, what lifestyle changes move the needle, and how fast improvement typically shows up.
Comparisons
How FixFirst compares to general-purpose AI and other blood test platforms — on the cases that matter.
FixFirst vs ChatGPT: Blood Test Analysis Compared
5 specific failure modes where general AI misses: sex-adjusted thresholds, borderline zones, priority ranking across multiple abnormal markers, guideline-anchored recommendations, and consistent output. With a direct comparison table.
FixFirst vs InsideTracker: Which Is Right for You?
InsideTracker runs its own tests and builds a longitudinal picture. FixFirst analyzes blood work you already have. The comparison covers cost, depth, use cases, and who each platform actually serves best.
Free Blood Test Analysis: What's Available and What Each Does Well
A comparison of free options for interpreting blood work — including general AI, consumer-facing lab portals, and purpose-built analyzers. What each handles well and where each falls short.
Upload any lab report (PDF, JPG, or PNG) and get your top 3 health priorities ranked by clinical urgency — including the borderline markers covered in these guides.
Analyze My Blood Test →