What Blood Tests Do Doctors Order When a Child Is Not Growing Normally?
The standard workup covers nutrition, thyroid, gut absorption, hormones, and (in girls) chromosomes. Here is the actual list, what each test looks for, and what a normal result means.
The standard first-tier workup
When a child's growth velocity is below age-appropriate range or their percentile is dropping, pediatricians typically order a defined panel of blood tests. Most are inexpensive and require a single blood draw. The goal is to rule out treatable causes before considering endocrine referral.
The typical tests and what each is looking for
- CBC (complete blood count). Looking for anemia, infection, or blood disorders. Iron-deficiency anemia can slow growth.
- Comprehensive metabolic panel. Kidney function, liver function, electrolytes. Chronic kidney or liver disease affects growth.
- TSH and free T4. Thyroid function. Hypothyroidism is a well-known cause of slow growth in children and is easily treated.
- tTG-IgA (with total IgA). Celiac disease. Undiagnosed celiac is a common and treatable cause of growth failure.
- IGF-1 (insulin-like growth factor 1). Surrogate marker for growth hormone activity. Low IGF-1 raises suspicion for growth hormone deficiency.
- IGFBP-3. Companion marker to IGF-1, more sensitive in younger children.
- ESR or CRP. Inflammation markers. Chronic inflammatory conditions can slow growth.
- Vitamin D level (25-OH vitamin D). Deficiency is common and can affect bone health.
- Karyotype (girls only). To rule out Turner syndrome. Not typically ordered for boys unless specific features are present.
What each pattern of results suggests
- All normal. Likely familial short stature or constitutional delay. Reassuring.
- High TSH, low free T4. Hypothyroidism. Treated with daily levothyroxine.
- Positive tTG-IgA. Presumptive celiac disease. Confirmed with endoscopy and biopsy.
- Low IGF-1 for age. Screens positive for possible growth hormone deficiency. Referral to pediatric endocrine for stimulation test.
- Iron-deficiency anemia. Iron supplementation and dietary changes. Growth typically catches up.
What is NOT usually in the first-tier panel
- Cortisol (only if adrenal insufficiency is suspected).
- Sex hormones (only if puberty is delayed or ambiguous).
- Full pituitary panel (only if endocrine referral is triggered).
- Genetic testing beyond karyotype (only if specific syndrome is suspected).
What imaging goes with the labs
The most common companion test is a bone age x-ray of the left wrist. It shows how much growth plate is still open and helps distinguish constitutional delay (bone age behind chronological age but growth is on track relative to bone age) from other causes.
How to prepare
- Bring 6-12 months of dated height measurements.
- Bring both parents' heights.
- Note any puberty signs and when they started.
- List all medications and supplements.
- If celiac testing is on the list, do not put him on a gluten-free diet before testing (it invalidates the result).
Height data uses the CDC 2000 Growth Charts for boys. This page is parent education, not medical advice or diagnosis. If you have concerns about your son's growth, talk to his pediatrician, ideally with 6-12 months of measurements in hand. © 2026 The Growth Path.