Idiopathic Short Stature (ISS): What Parents Need to Know

July 11, 2025

What Is Idiopathic Short Stature (ISS)?

Idiopathic short stature (ISS) is a medical term for children who are significantly shorter than their peers—with a height below the 3rd percentile for age and sex—but have no identifiable medical, hormonal, or genetic cause for their short stature. The word “idiopathic” means the cause is unknown, and ISS is a diagnosis of exclusion, made only after other possible causes of short stature have been ruled out.

What Conditions Must Be Ruled Out?

Before diagnosing ISS, doctors systematically check for other causes of short stature. Here’s what they look for:

Endocrine Disorders

Growth hormone deficiency (GHD): The pituitary gland doesn’t produce enough growth hormone, leading to slow growth, delayed bone age, and often a child who is much shorter than expected for their age.
Hypothyroidism: Low thyroid hormone levels slow metabolism and growth. Children may have fatigue, weight gain, dry skin, and poor school performance.
Cushing’s syndrome: Excess cortisol (a stress hormone) causes slow growth, rapid weight gain (especially in the face and trunk), and sometimes high blood pressure or easy bruising.

Genetic Syndromes

Turner syndrome: Affects only girls. Features include short stature, webbed neck, broad chest, and sometimes heart or kidney problems. Usually diagnosed with genetic testing.
Noonan syndrome: Can affect boys or girls. Children may have short stature, distinctive facial features, heart defects, and sometimes developmental delays.
SHOX gene deficiency: A genetic issue causing short stature and sometimes abnormal limb proportions.

Chronic Diseases

Celiac disease: Gluten intolerance damages the gut, leading to poor nutrient absorption, diarrhea, and poor growth.
Inflammatory bowel disease: Chronic gut inflammation causes abdominal pain, diarrhea, poor appetite, and slowed growth.
Chronic kidney or heart disease: Long-term organ problems can reduce appetite and nutrient absorption, leading to growth delays.

Nutritional Deficits

Malnutrition or vitamin/mineral deficiencies: Inadequate intake or absorption of nutrients leads to being underweight, slow growth, and signs like pale skin, brittle hair, or frequent illness.

Skeletal Disorders

Achondroplasia or other skeletal dysplasias: Genetic bone disorders cause disproportionate short stature (short limbs, normal trunk), and visible skeletal differences.

Psychosocial Factors

Emotional deprivation or chronic stress: Severe stress or neglect can suppress growth; children may catch up if their environment improves. Lab tests are typically normal.

Only after these and other potential causes are excluded through medical history, examination, lab tests, and sometimes genetic testing, can a diagnosis of ISS be made.

How Is ISS Diagnosed?

Height: Below the 3rd percentile for age and sex, or more than 2 standard deviations below the mean.
Growth rate: May be normal or slightly reduced, but not as low as in most chronic diseases.
Physical exam: No signs of chronic illness or syndrome.
Lab tests: Normal thyroid, growth hormone, and screening for chronic diseases.
Bone age: X-ray of the hand/wrist matches or is only mildly delayed compared to chronological age.

How Common Is ISS?

ISS is the most common diagnosis for children referred to pediatric endocrinologists for short stature.

Up to 60–80% of children with short stature have ISS after other causes are excluded.
About 2–3% of children in the general population may meet ISS criteria at some point.

Treatment Options for ISS

The decision to treat ISS, particularly with growth hormone, is complex and requires careful consideration, often involving discussions between physicians and families regarding potential benefits and limitations.

Growth Hormone (GH) Therapy

FDA-approved in the U.S. for children with height more than 2.25 SD below the mean and poor predicted adult height.
Daily injections over several years can increase growth rate and improve final adult height by an average of 1.5–3 inches (4–7 cm) in responsive children.
Not all children respond equally; genetics and age at treatment start matter.
While GH therapy can increase final adult height, its impact may be modest. Some experts view it as a "luxury" therapy for ISS, as the treatment aims to increase height in otherwise healthy children, rather than addressing an underlying deficiency. It is typically considered when the child is at the extreme end of the short stature spectrum for which no cause is identified, and the potential benefit outweighs the burden and cost of daily injections

Psychological Support

Short stature can affect self-esteem and social confidence. Counseling or support groups can help children and families cope positively.

Prognosis and Long-Term Outlook

Final Adult Height: Most children with ISS will remain shorter than average as adults, but many reach a height within the lower end of the normal range.
Health: ISS does not increase the risk of other health problems, and children are otherwise healthy.
Quality of Life: With support, most children with ISS lead normal, healthy lives. Early diagnosis and appropriate management can help maximize both height potential and emotional well-being.

Supporting Healthy Growth: iKids-Growth

While ISS and other medical causes require professional diagnosis and treatment, children with height above the 3rd percentile but still on the shorter side may benefit from additional growth support like iKids-Growth.

iKids-Growth is a natural, evidence-based dietary supplement designed to help children and adolescents reach their full height potential by gently supporting the body’s own growth pathways—specifically the GH–IGF-1 axis. Unlike medications or hormone therapies, iKids-Growth is not a drug and is not intended to treat or cure any disease, including growth disorders like ISS. Instead, it works best for healthy children whose growth plates are still open and who want to optimize their growth with a safe, science-backed approach.

Always consult your healthcare provider before starting any supplement, especially if your child is below the 3rd percentile or has any health concerns.

Still have questions about your child’s height growth?
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FAQ

Q1: Can a child outgrow ISS without treatment?
Some children with ISS reach a height within the lower normal range as adults without treatment, but they usually stay shorter than peers. GH therapy may help, but not all qualify or respond well.

Q2: What are the warning signs that short stature could be caused by an underlying disease?
Red flags include very rapid decline on the growth chart, symptoms like chronic fatigue, unexplained weight loss, digestive problems, abnormal physical features, or a family history of genetic disorders. If you notice these, seek medical evaluation promptly.

Q3: Is iKids-Growth suitable for children diagnosed with ISS or other growth disorders?
iKids-Growth is not a medication and is not intended to treat ISS or any disease. It is designed for healthy children above the 3rd percentile who want to support their natural growth. For children with diagnosed growth disorders or who are below the 3rd percentile, consult a pediatric endocrinologist before considering any supplement.