Modern diagnostics generate more data than most clinicians have time to interpret. We cover what each test measures, the population it was validated in, the false-positive rate, and the actions a result should and should not trigger.
A test's positive predictive value depends on how likely the condition is before the test. Screening low-risk populations produces mostly false positives, even with 'accurate' tests.
Lab reference intervals describe the middle 95% of the testing population — not a healthy target. Ferritin, vitamin D, and TSH ranges in particular invite over- and under-treatment.
Most common variants shift risk by single-digit percentages. Polygenic scores are improving but rarely change individual management today.
Whole-body MRI and full-body CT find 'something' in 15–30% of healthy adults. Most are benign, but the workup carries real morbidity, cost, and anxiety.
Genetic analyses across 654,783 participants show ApoB is the principal driver of coronary heart disease risk among atherogenic lipoproteins; LDL-C and triglycerides add no independent risk after ApoB is accounted for. Strongest case yet for ApoB as the primary lipid target.
Richardson et al., PLOS Med, 2020 · Source ↗
National Lipid Association consensus that Lp(a) should be measured at least once in adulthood; levels above ~50 mg/dL (125 nmol/L) are an independent risk enhancer that reframes prevention thresholds. Largely genetically determined and stable across the lifespan.
Koschinsky et al., J Clin Lipidol, 2024 · Source ↗
Patient-level meta-analysis of 31,245 patients on statins showed hs-CRP and IL-6 were as strong as LDL-C in predicting future MACE. Supports residual inflammatory risk as a treatment target.
Ridker et al., Lancet, 2023 · Source ↗
Pooled MESA cohort analyses show CAC = 0 confers ~10-year MACE risk under 1% in asymptomatic adults, while CAC ≥100 reclassifies many patients to statin eligibility. Endorsed by 2018 ACC/AHA cholesterol guidelines for borderline/intermediate risk.
Grundy et al., Circulation, 2019 (ACC/AHA) · Source ↗
Pooled data show clinically significant findings in 1–2% of self-referred adults but incidental findings in 15–35%, with downstream workup costs and morbidity. Useful for high-risk individuals (e.g., Li-Fraumeni); not supported as general screening.
Hegenscheid et al., Eur Radiol, 2013 · Source ↗
Grade B recommendation for screening women ≥65 and younger postmenopausal women at increased risk; DEXA is the reference standard for bone mineral density and fracture risk estimation. Same scan provides validated body composition outputs.
USPSTF, JAMA, 2018 · Source ↗
Clinical Pharmacogenetics Implementation Consortium publishes evidence-graded gene-drug guidelines (CYP2C19/clopidogrel, CYP2D6/codeine, HLA-B/abacavir, TPMT/thiopurines). The 'A' level guidelines are the practical core of pharmacogenomics.
Relling & Klein, Clin Pharmacol Ther, 2011 (and updates) · Source ↗
Identifying BRCA1/2, PALB2, Lynch syndrome and related variants alters surveillance intervals, prophylactic surgery, and PARP inhibitor eligibility. Cascade testing of first-degree relatives multiplies clinical impact.
NCCN Guidelines (current version) · Source ↗
Comparison of 23andMe-style single-variant panels against clinical sequencing showed high false-negative rates; consumer reports test only 3 of >1,000 known pathogenic BRCA variants. Confirmatory clinical-grade testing required before any medical action.
Tandy-Connor et al., Genet Med, 2018 · Source ↗
AGA finds insufficient evidence to recommend stool microbiome testing for diagnosis or treatment outside of C. difficile and select inflammatory conditions. Personalized diet recommendations from these tests are not yet evidence-based.
Staller et al., Gastroenterology, 2024 · Source ↗
Reviews show CGM detects post-prandial excursions invisible to fingerstick testing, but evidence that non-diabetic excursions predict long-term outcomes remains limited. Behavioral feedback effects on diet are the most consistently demonstrated benefit.
Holzer et al., Nutrients, 2022 · Source ↗
6,238 symptomatic patients evaluated with the Galleri MCED test; overall sensitivity 66.3%, specificity 98.4%, with sensitivity rising sharply with stage. Mortality benefit data from large RCTs (e.g., NHS-Galleri) are still pending.
Nicholson et al., Lancet Oncol, 2023 · Source ↗