Low Birth Weight A Risk Factor For Focal Segmental Glomerulosclerosis
Focal segmental glomerulosclerosis is scar tissue that forms in areas of the kidney that filter certain things out of the body. These areas are called glomeruli and each kidney has thousands of glomeruli.
The cause of focal segmental glomerulosclerosis is usually unknown, but recently some evidence was unveiled that leads to scrutinizing a risk factor – low birth weight.
Birth history is often not screened for by kidney specialists who take care of adult patients, so this risk factor is often overlooked. Low birth weight, defined as a weight less than 5.5 lbs., is known to be a risk factor for adult hypertension, coronary heart disease, stroke, diabetes and others. However, until recently, its association with the development of focal segmental glomerulosclerosis has not been reported.
To investigate this potential link, Dr. D’Agati of the Columbia University College of Physicians and Surgeons in New York City, NY, and her colleagues studied six patients who had clinical indications of this condition and who were born prematurely and were low birth weight. The average birth weight was 3.3 lbs. and all were born between 22 and 30 weeks gestation. Normal gestation is considered to be between 37 and 42 weeks.
All of the tests and measurements the physicians conducted determined that these patients had developed focal segmental glomerulosclerosis. The authors noted that because new nephrons are not formed after birth, an individual’s supply of nephrons is dependent on the environment in utero. If an infant is born with an insufficient supply of nephrons, their kidneys may become strained, which can lead to declines in kidney function over time.
These physicians concluded that “premature babies with very low birth weights may develop renal disease in adolescence or adulthood that is a consequence of retarded kidney development and overwork of the kidney,” said Dr. D’Agati. “Doctors need to be aware of this association so that the medical condition is not misdiagnosed or missed completely and treated inappropriately,” she added.
Although the cause of focal segmental glomerulosclerosis remains unknown, a small number results from reflux nephropathy. The condition affects both children and adults, although males are affected more often than females and it occurs more frequently in African-Americans.
Focal segmental glomerulosclerosis causes about 10-15% of all cases of nephrotic syndrome. The symptoms are foamy urine, generalized edema, weight gain and poor appetite. Treatment is quite stringent with the limiting of protein to 1 gm/kg body weight/day, a low fat diet, salt-free diet, fluid restriction, anti-inflammatory medications, antibiotics, vitamin D supplementation, dialysis and even kidney transplant. No prevention is known to date.
These works represent groundbreaking news, but remember there were only six patients involved. Physicians should weigh this information carefully and be on the lookout for a relationship between their own low birth weight patients and this condition before we can come up with epidemiological conclusions. More study and observations are obviously needed before recommendations can be made. The conclusions of Dr. D’Agati and colleagues are interesting and time sensitive, but limited to the number of subjects observed.
See also http://www.asn-online.org/
About the author
Kathy Shattler received her Master of Science degree from Michigan State University in E. Lansing Michigan in Human Nutrition. Her twenty-two years of practice includes holding positions as a Lecturer, Chief Clinical Dietitian and Program Manager. Kathy is the Founder of Nutri-Care Consulting and is currently the Nutrition Director of www.CEU4U.COM, an online continuing education management company for Registered Dietitians and Dietetic Technicians.
