General considerations:
- Order labs with a clear clinical question in mind: If a result won’t change your diagnosis or management, don’t order it.
- Consider pre-test probability: Low probability of disease + non-specific symptoms → lab tests are more likely to give false positives than help.
- Always review medical records to see if labs were recently ordered (to avoid unnecessary repetition) and follow condition-specific Policy for frequency.
CBC:
- Routine CBC is Not Needed as part of Routine Annual HTN or DM labs (unless needed for other indications or Clinical suspicions)
- it can be a routine part of Annual follow-up visits in Asymptomatic patients with high-risk chronic conditions. (e.g. CKD, Rheumatological disease, IBD)
- Minimum intervals of Follow-up & monitoring:
- Iron deficiency Anemia: every 4-8 weeks till Hgb normalize, then repeat only if symptoms recur.
- Asymptomatic with normal CBC: don't order if done <12 months
Ferritin:
- Order only if symptomatic or clinically indicated
- In cases of fatigue, counsel All patients regarding missed causes:
- Lifestyle: sedentary lifestyle, overwork/burnout, dehydration
- Sleep: sleep deprivation, Poor sleep hygiene, Obstructive sleep apnea.
- Psychological: depression, anxiety, stress-related, adjustment disorder.
- Medical: uncontrolled chronic diseases & side effects of medications
- In cases of persistent hair-fall with normal workup, aim for ferritin >80 and evaluate for telogen effluvium, excessive traction, harsh hair products, quality of household water sources (e.g. equip water filters if hard water/old piping/water heaters are frequently used but not well-maintained).
Fasting blood glucose & HbA1C:
- Routine DM Screening can be done with either FBG or HBA1C
- In-office fasting serum glucose testing is a rapid, inexpensive, and valid diagnostic tool to screen for diabetes. However, it's widely underutilized.
- Targeted screening groups:
| Age ≥ 35 years | All patients regardless of risk factors |
| Age < 35 years | If BMI ≥ 25 (85th percentile in children) PLUS any risk factor for DM |
- Frequency of re-testing & screening
| Scenario | Recommended screening interval |
| Normal result | every 3 years |
| Prediabetes | yearly |
| History of GDM | every 1-3 years |
| DM patient follow-up | every 3-6 months (depends on control) |
Lipid profile:
- Targeted screening groups:
| Males ≥ 35 years Females ≥ 45 years. | All patients regardless of risk factors |
| Other Age groups | if high-risk (e.g., diabetes, hypertension, smoking, obesity, family history of premature CVD) |
| Scenario | Recommended testing interval |
| normal result and low-risk | Every 5 years |
| high-risk or abnormal results (not on statins) | Every 1–3 years |
| statins are initiated | Recheck lipids in 4–12 weeks after starting or changing therapy. Once LDL-C is at target and stable → repeat every 6–12 months to ensure ongoing control. |
Renal functions:
- Renal functions are diagnostic or monitoring tools, order only if renal disease is suspected
- not screening tests in healthy, asymptomatic patients without risk factors.
- When used for monitoring in diabetes, hypertension, or CKD risk: Repeat every 6–12 months if stable; more often if worsening or starting/changing therapy (e.g., ACEi, NSAIDs).
- Always assess kidney function in diabetes using estimated GFR (eGFR) rather than serum creatinine alone, as eGFR accounts for age, sex, and race — providing an accurate measure of renal function; a ‘normal’ creatinine can be misleading and mask early chronic kidney disease.”
Liver function test:
- LFTs are diagnostic or monitoring tools, not screening tests in healthy, asymptomatic patients without risk factors.
- Clinical indications: include Unexplained jaundice or RUQ pain, Suspected liver disease (viral hepatitis risk, alcohol use, NAFLD), Monitoring hepatotoxic drugs (e.g., statins, methotrexate), Abnormal findings on imaging or incidental lab abnormalities.
- Frequency: Every 3–6 months if on hepatotoxic medications. Otherwise, guided by clinical course (e.g., elevated enzymes → recheck in 2–4 weeks to confirm or trend).
Thyroid functions:
- TFT are diagnostic or monitoring tools, not screening tests in healthy, asymptomatic patients — except during the first antenatal visit in pregnancy, where screening is recommended.
- Indications: include symptoms suggestive of thyroid disease (other than fatigue alone), New atrial fibrillation or unexplained heart failure, Goiter or thyroid nodules, Infertility or menstrual irregularities, Monitoring known thyroid disorders or replacement therapy.
- Frequency: in stable hypothyroid patients on therapy: every 6–12 months. After dose adjustments: recheck TSH after 6 weeks.
Vitamin D:
- Routine testing is not recommended as part of an annual or general health check in asymptomatic, low-risk adults → no evidence of benefit from widespread screening
- Patients should be counseled that a daily maintenance dose of 1,000 IU not only prevents repeated cycles of high-dose replacement, deficiency recurrence, unnecessary re-testing, and re-treatment, but can also effectively treat mild deficiency (serum 25-OHD 20–30 ng/mL), ensuring long-term sufficiency with fewer interventions
- Indications: include patients with osteoporosis or osteopenia, CKD stages 3–5, Malabsorption syndromes (e.g., celiac, Crohn’s, gastric bypass), Unexplained fractures, bone pain, or muscle weakness, Certain medications increasing deficiency risk (e.g., anticonvulsants, glucocorticoids).
- Frequency: repeated once, 3–6 months after starting supplementation in deficient patients to confirm correction. Otherwise, no need for routine repetition in stable patients on maintenance doses.
Vitamin B12:
- Routine testing is not recommended as part of an annual or general health check in asymptomatic patients without risk factors.
- Indications: include Macrocytic anemia (MCV >100 fL) or unexplained anemia, Neurologic symptoms: paresthesia, neuropathy, ataxia, cognitive changes, Malabsorption risk (e.g., gastrectomy, gastric bypass, Crohn’s, celiac), Long-term metformin or proton pump inhibitor (PPI) use (>3–5 years), Strict vegan diet without supplementation.
- Frequency: repeated once, 2–3 months after starting treatment in deficiency to confirm correction. No routine monitoring needed once stable on maintenance therapy unless new symptoms arise.
Folate:
- Rarely indicated, except in specific cases like macrocytic anemia with normal B12 to distinguish folate deficiency, or in Malabsorption conditions.
Tips on Counseling patients when labs are not indicated
- Emphasize personalized, evidence-based care with reassurance: “I want you to know that every test I order is chosen carefully for you — not just because it’s possible to order, but because it’s truly proven to benefit your health at your age and with your specific situation. By focusing only on what’s necessary, we avoid needless worry and make decisions that actually move us toward better answers and better health.”
- Explain how unnecessary tests can cause hidden harm, with empathy: “I completely understand how it can feel like ‘more tests must be better,’ especially if they’re free. But the truth is, unnecessary tests can show harmless variations that look abnormal, leading to stress, more appointments, and sometimes even risky procedures you don’t need. My goal is to protect you from these pitfalls, not just check boxes.”
- Connect symptoms to tests with clarity and practical examples: “I hear your concerns, and it’s important to me that you feel confident we’re on the right path. But for example, checking your calcium level without any signs of calcium problems won’t help us — because your body keeps calcium tightly controlled, and it’s almost never the reason behind your symptoms unless we find clues on your exam or history. By focusing on tests linked directly to what we find in your exam, we’ll get the answers we actually need without sending you on a long chase after lab values."
Dr. Fahad Saad Almutairi, MBBS, SBFM, TOT