Catch-Up Growth Definition
Catch-up growth is an accelerated growth velocity above normal limits for age that occurs after removal of a growth-inhibiting condition, allowing a child to return toward their genetic growth trajectory.
Core Defining Criteria
To qualify as true catch-up growth, four specific criteria must be met 1, 2, 3:
- Criterion 1: A growth-inhibiting condition must be present (malnutrition, chronic disease, endocrine disorder) 1, 2
- Criterion 2: This condition causes a documented reduction in linear growth velocity below normal for age 2, 3
- Criterion 3: The growth-inhibiting condition is alleviated or removed 2, 3
- Criterion 4: Growth velocity subsequently increases to above-normal rates for the child's age 1, 2
Clinical Characteristics
Growth Pattern
Catch-up growth follows a characteristic pattern 1:
- Immediate phase: Growth acceleration with abnormally high velocity immediately after removing the growth restriction 1
- Deceleration phase: Progressive slowing of growth velocity as the child approaches their original growth channel 1
- Endpoint: Growth returns to the child's genetic trajectory (target height range) 2
Measurement Standards
Height velocity is the primary metric, but change in height standard deviation score (SDS) is more appropriate for quantifying catch-up growth 2. In clinical practice, catch-up growth in children with chronic kidney disease demonstrates cumulative increases of 1.1-1.9 SDS over 5-6 years of treatment 4.
Types of Catch-Up Growth
Three distinct patterns exist 5:
- Type 1: Rapid elimination of height deficit with immediate return to original growth curve 5
- Type 2: Delayed growth initially, but prolonged growth period compensates for the arrest 5
- Type 3: Mixed pattern combining features of both types 5
Each type may be complete or incomplete 5.
Age-Dependent Recovery Potential
Complete catch-up growth is possible in infants and young children, but NOT in children near or during puberty 1. This critical distinction reflects:
- Infancy: Most sensitive period for growth-suppressing effects; deficits can become irreversible if prolonged 4
- Prepubertal children: Substantial recovery potential with appropriate intervention 4
- Pubertal/adolescent children: Limited or no catch-up growth capacity due to advancing skeletal maturation 1, 5
Clinical Context Examples
Chronic Kidney Disease
In children with CKD, spontaneous catch-up growth is monitored for at least 1 year post-transplantation before considering growth hormone therapy 4. However, renal transplantation does not uniformly result in catch-up growth 4.
Malnutrition
Recovery from nutritional deficits may show incomplete catch-up growth, particularly when undernutrition occurs early in life 3. Dramatic improvements in living conditions (such as adoption or foster care) lead to some but incomplete recovery in linear growth 3.
Growth Hormone Therapy
Increased growth velocity from GH therapy is accurately called catch-up growth ONLY in children with documented GH deficiency; in other disorders it should be termed "growth enhancement" 2.
Important Clinical Distinctions
Not True Catch-Up Growth
The following scenarios do NOT meet criteria for catch-up growth 2, 3:
- Observational studies without documented growth-inhibiting conditions 3
- Studies using absolute height rather than velocity measurements 3
- Growth acceleration without prior alleviation of an inhibiting condition 3
- Post-intrauterine growth retardation acceleration (does not meet all criteria despite common terminology) 2
Differentiation from Pubertal Growth Spurt
Catch-up growth is superficially similar to pubertal growth spurt but differs fundamentally 1:
- Velocity curve shape: Different patterns 1
- Maturity stage: Occurs at different developmental stages 1
- Mechanisms: Entirely different regulatory mechanisms 1
Regulatory Mechanisms
The mechanisms controlling catch-up growth remain incompletely understood 1. Current evidence suggests:
- More likely involved: Serum growth factors, receptor changes, or genetically programmed cells 1
- Less likely involved: Classical growth-promoting hormones alone 1
- Two competing hypotheses: Neuroendocrine hypothesis (lacks experimental support) versus growth plate hypothesis (cannot fully explain human catch-up growth patterns) 2
Practical Assessment
For individual children, complete catch-up growth cannot be definitively determined until final height is reached 2. If final height falls within the target height range (mid-parental height ±2 SDS), catch-up growth is considered probably complete 2. For patient groups, mean final height close to mean target height indicates complete catch-up growth 2.