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Urinary growth hormone measurements in children with renal insufficiency
G Turner1, A Skinner, J S Woodhead
1Department of Medical Biochemistry, University Hospital of Wales, Heath Park, Cardiff, UK.
Insights
Urinary growth hormone (UGH) levels are significantly elevated in children with renal insufficiency due to kidney dysfunction. These findings suggest UGH is unreliable for assessing pituitary function in such patients.
Area of Science:
- Pediatric Nephrology
- Endocrinology
- Biochemistry
Background:
- Intrinsic renal factors can influence urinary growth hormone (UGH) measurements.
- Assessing hypothalamo-pituitary function in children with renal insufficiency requires reliable biomarkers.
Purpose of the Study:
- To compare UGH excretion in children with varying degrees of renal insufficiency versus healthy controls.
- To investigate the impact of renal function on UGH levels and identify potential causative factors.
Main Methods:
- Compared UGH excretion in 21 children (aged 4-16) with renal insufficiency and 10 control subjects (aged 5-13).
- Measured plasma creatinine, urinary beta 2-microglobulin, and albumin excretion.
- Categorized patients into Group A (creatinine > 120 mumol/L) and Group B (creatinine < 120 mumol/L).
Main Results:
- Group A exhibited 100- to 1000-fold higher UGH levels (median 2649 microU) compared to Group B (median 7.5 microU) and controls (median 4.0 microU).
- Elevated urinary beta 2-microglobulin levels were observed in Group A (median 11,637 microgram).
- No significant difference in albumin excretion between groups A and B, except in nephrotic syndrome patients in Group B.
Conclusions:
- Abnormal renal function profoundly affects growth hormone excretion in children.
- Proximal tubular dysfunction is suggested as the cause of elevated UGH.
- Urinary growth hormone measurements are unreliable for assessing hypothalamo-pituitary function in pediatric renal insufficiency.
Abstract:
It has been reported that intrinsic renal factors could affect urinary growth hormone (UGH) measurements. We compared UGH excretion in 21 children aged 4-16 years, with various degrees of renal insufficiency, with that in 10 control subjects aged 5-13 years. We found 100- to 1000-fold elevations in UGH in children with plasma creatinine concentrations > 120 mumol/L (Group A) compared with patients with plasma creatinine concentrations < 120 mumol/L (Group B) and control subjects. UGH excretion (microU) in the three groups was as follows: group A 804-8556 (median 2649); group B 1.0-85 (median 7.5); and controls 2.6-7.3 (median 4.0). Elevated urinary beta 2-microglobulin levels (microgram) were also observed in group A patients: 875-15,400 (median 11,637) as compared with group B, 1.0-104 (median 32) and controls, 3-18.7 (median 8.0). There was no significant difference in albumin excretion between groups A and B through six patients in group B with nephrotic syndrome (NS) excreted significantly more albumin (P < 0.05) than the other 15 patients investigated. Our data show that abnormalities of renal function have a profound effect on growth hormone excretion and we suggest proximal tubular dysfunction as the causative factor. We conclude that UGH measurements do not provide a reliable means of assessment of hypothalamo-pituitary function in patients with renal insufficiency.