Longitudinal growth in chronic hypokalemic disorders

Area of Science:

• Pediatric Nephrology
• Endocrinology
• Growth Biology

Background:

• Growth retardation is a significant complication in children with primary tubular disorders, even with supportive care.
• Chronic hypokalemia, common in certain tubulopathies, is linked to impaired growth through poorly understood mechanisms.
• Previous studies suggest a connection between hypokalemia and growth hormone (GH) / insulin-like growth factor I (IGF-I) axis alterations.

Purpose of the Study:

• To investigate the mechanisms by which hypokalemia impairs growth in pediatric kidney disorders.
• To examine the effects of potassium depletion on the growth hormone and insulin-like growth factor I axis.
• To understand the resistance to growth hormone observed in hypokalemic conditions.

Main Methods:

• Utilized a rat model of potassium depletion to study growth and hormonal changes.
• Assessed body length, weight, renal hypertrophy, and circulating IGF-I levels.
• Measured IGF-I messenger ribonucleic acid (mRNA) in the tibial growth plate and evaluated GH signaling in the liver.

Main Results:

• Hypokalemic rats exhibited reduced body length and weight gain compared to controls, despite similar food intake.
• Renal hypertrophy was observed in hypokalemic rats.
• These rats showed decreased circulating IGF-I, reduced tibial growth plate IGF-I mRNA, and resistance to exogenous GH.
• No intracellular GH signaling defects were found in the liver, but epiphyseal cartilage chondrocytes were abnormally hypertrophied.

Conclusions:

• Potassium depletion in a rat model leads to growth retardation, partly due to impaired IGF-I axis signaling and GH resistance.
• Severe disturbances in epiphyseal cartilage chondrocytes are a key feature of hypokalemia-induced growth impairment.
• These findings highlight the critical role of maintaining normal potassium levels for proper growth in children with tubular disorders.