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Urinary excretion of IGF-I and growth hormone in children with IDDM
T Quattrin1, C H Albini, E O Reiter
1Department of Pediatrics, Children's Hospital of Buffalo, NY 14222.
Insights
Children with insulin-dependent diabetes mellitus (IDDM) excrete less urinary insulin-like growth factor I (IGF-I) and growth hormone (GH) than healthy children. This difference may be related to the duration of the disease.
Area of Science:
- Endocrinology
- Pediatrics
- Metabolic Disorders
Background:
- Insulin-dependent diabetes mellitus (IDDM) is a chronic metabolic disorder affecting children.
- Growth hormone (GH) and insulin-like growth factor I (IGF-I) are crucial for growth and metabolism.
- Urinary excretion of IGF-I and GH may reflect systemic levels and metabolic status.
Purpose of the Study:
- To compare urinary IGF-I and GH output in prepubertal and pubertal children with IDDM versus non-diabetic controls.
- To investigate the relationship between urinary IGF-I and GH excretion and metabolic control (HbA1) in children with IDDM.
Main Methods:
- Radioimmunoassays were used to measure urinary IGF-I and GH in 12-hour overnight collections from 30 children with IDDM and 31 healthy controls.
- Urine samples were dialyzed, concentrated, and lyophilized prior to analysis.
- Subjects were stratified by age (prepubertal and pubertal) and diabetes status.
Main Results:
- IDDM subjects showed significantly lower urinary IGF-I and GH output per kilogram body weight compared to controls.
- No significant differences in urinary IGF-I or GH output were found between prepubertal and pubertal children within either the IDDM or control groups.
- A strong positive correlation was observed between urinary IGF-I and GH excretion (r = 0.85).
- No correlation was found between urinary IGF-I or GH output and HbA1 levels.
Conclusions:
- Long-standing IDDM is associated with significantly lower urinary IGF-I and GH levels compared to healthy individuals.
- Further research is needed to determine if these urinary peptide changes are present at diagnosis or develop over time with disease duration.
Objective:
To compare the urinary output of insulinlike growth factor I (IGF-I) and growth hormone (GH) in prepubertal and pubertal children with insulin-dependent diabetes mellitus (IDDM) versus nondiabetic subjects and to analyze the relationship between the urinary excretion of these peptides and degree of metabolic control.
Research Design And Methods:
Group 1 included 30 IDDM patients who had had diabetes for 4.9 +/- 0.7 yr and had normal renal function (mean age 11.6 +/- 0.9 yr); group 2 consisted of 31 control subjects (mean age 9.2 +/- 0.6 yr). Sensitive radioimmunoassays were used to measure IGF-I and GH in urine aliquots from 12-h timed overnight collections that had been dialyzed, concentrated 50-fold, and lyophilized.
Results:
Significantly lower IGF-I and GH outputs per kilogram body weight per 12 h were observed in IDDM subjects compared with control subjects. When data were expressed per kilogram of body weight, no difference was observed between the urinary output of IGF-I and GH between prepubertal and pubertal subjects within group 1 or group 2. The prepubertal children had significantly lower HbA1 than the pubertal population; however, no correlation was found between urinary output of IGF-I or GH and HbA1. A positive correlation was observed between urinary IGF-I and GH (r = 0.85, P less than .001).
Conclusions:
Patients with long-standing IDDM excrete significantly lower urinary levels of IGF-I and GH compared with normal subjects. Serial measurements of these peptides from onset of IDDM are needed to define whether the changes observed are present at diagnosis or are secondary to duration of disease.