Pediatric nephrology

Anatomy or system affected: Abdomen, blood, kidneys, urinary system

Definition: The specialty involving the diagnosis and treatment of kidney disorders and diseases in children and adolescents

Science and Profession

Pediatric nephrology is a major subspecialty limited to children and adolescents that involves the study of normal and abnormal kidney (renal) function. This discipline not only relates to kidney diseases and renal dysfunction but also places heavy emphasis on the kidneys’ adaptive role in many diseases and disorders of nonrenal origin. Pediatric nephrologists are doctors of medicine or osteopathy who have completed three years of pediatricresidency training, followed by two or three years in a pediatric nephrology fellowship.

The kidneys are among the most interesting and complex organs in the human body. Kidney diseases often involve the fields of immunology, oncology, genetics, chemistry, physiology, biotechnology, and both gross anatomy and microanatomy (histology). While the cognitive aspects of nephrology dominate the day-to-day work of its specialists, hands-on procedures such as renal biopsies and renal dialysis add variety and interest. Pediatric nephrologists spend approximately 60 percent of their time dealing with primary renal disease, while 40 percent of their time is spent with diseases and conditions of nonrenal origin, especially in critically ill children.

While the kidneys have many functions, their main role is filtering metabolic wastes from the blood and eliminating them via the urinary tract. The process of filtering blood, concentrating its wastes, and reabsorbing water and useful metabolic components (such as protein, sodium, and potassium salts) is accomplished with an elaborate system of passive and active mechanisms in the nephrons in each kidney. The kidneys respond to many factors, including blood volume, blood pressure, the salt and acid content of the blood, nitrogenous wastes (urea), and even hormonal and neural (nerve) stimuli. The kidneys deliver feedback to other vital organs with chemical messengers via the bloodstream and also through the nervous system.

Several key areas in pediatric nephrology make it unique from adult nephrology: immature renal function in infancy, growth retardation in chronic renal disease, and the role of genetics.

Diagnostic and Treatment Techniques

The patient’s history, a physical examination, and routine urinalysis are the cornerstones of diagnosis in nephrology. Urinalysis is one of the most available, fastest, and least expensive tests in clinical medicine. Frequently, diagnosis is made or suspected from a routine urinalysis done in screening or as part of a routine physical. The test can reveal evidence of infection; microscopic traces of blood, protein, or sugar; and many other abnormalities. Often, early diagnosis of silent renal disease will aid in early intervention, treatment, and the prevention of advanced disease and morbidity. In addition to blood chemistry tests—such as for sodium, potassium, glucose (sugar), and blood, urea, and nitrogen (BUN)—many quantitative tests are available to measure other aspects of renal function.

Dramatic advances in imaging techniques have been made. X-rays, ultrasound, computed tomography (CT) scans, magnetic resonance imaging (MRI), and nuclear scans are making detailed anatomical diagnosis possible in noninvasive ways. Very small tumors and structural abnormalities can be identified. Some scans can provide useful information on renal function.

Renal biopsy with a percutaneous (through-the-skin) technique, using a large-bore needle, was developed in the 1960s. The samples allow detailed examination at microscopic and submicroscopic (electron microscopy) levels. Since many renal diseases reveal a characteristic thickening from immunoglobulin deposits and inflammation of membranes in the glomerulus, exact diagnoses are often made by biopsy alone or in conjunction with immunological tests.

In the early part of the twentieth century, the treatment of renal diseases was limited to symptomatic and supportive measures. By the 1940s and 1950s, the advent of antibiotics allowed definitive treatment of kidney and urinary tract infections. Since that era, chemotherapy and immunotherapy have developed rapidly, and many primary renal diseases are now being treated successfully by such methods. Immunotherapy also plays a major role in renal transplantation.

In chronic renal disease, in which the total renal function becomes inadequate to sustain life, children can be treated successfully with renal dialysis. Evolving from pioneer efforts in the 1960s and early 1970s, dialysis is now done routinely for such children, including infants. The effectiveness, safety, and efficiency of the procedure have improved dramatically. Now infants and toddlers usually have peritoneal (abdominal cavity) dialysis conducted at home. Older children usually have hemodialysis about three times a week at a dialysis center. The dialysis machine is connected to a cannula (tubing) that is placed in the patient’s arm.

Severe growth retardation is a major problem associated with chronic renal disease in children, often compounded by psychological problems such as severe depression. A combination of improved aggressive nutritional and metabolic support and treatment with growth hormone has improved the health and mental well-being of these children.

By the early 1970s, kidney transplantation was being performed on children. This operation is performed by urologists and pediatric surgeons. Originally, rejection rates and other complications were very high; however, results have improved dramatically over the decades. This procedure allows thousands of children to lead healthy, normal lives.

The study of renal function in newborns, especially premature ones, has led to sophisticated intensive care for critically ill infants. Pediatric nephrologists may also act as consultants for older children with critical illnesses, injuries, poisonings, and even trauma. Such cases often involve sophisticated intravenous (IV) fluid therapy. Because of temporary renal failure, some of these cases require dialysis.

Perspective and Prospects

The progress in renal dialysis and transplantation has been remarkable. Continued advances in effectiveness, success rates, safety, and convenience are certain. The gene that causes familial polycystic kidney disease has been identified. Such discoveries, coupled with advances in genetics, may revolutionize therapy and even prevent some renal diseases through genetic engineering.

Bibliography

Bock, Glenn H., Edward J. Ruley, and Michael P. Moore. A Parent’s Guide to Kidney Disorders. University of Minnesota Press, 1993.

Faris, Mickie Hall. When Your Kidneys Fail: A Handbook for Patients and Their Families. 3rd ed., National Kidney Foundation of Southern California, 1994.

Frank, J. David, John P. Gearhart, and Howard M. Snyder, eds. Operative Pediatric Urology. 2nd ed., Churchill Livingstone, 2002.

O’Callaghan, Chris A., and Barry M. Brenner. The Kidney at a Glance. Blackwell Scientific, 2000.

"Pediatric Nephrology Clinic." Mayo Clinic, 30 June 2023, www.mayoclinic.org/departments-centers/pediatric-nephrology-clinic/overview/ovc-20465380. Accessed 25 July 2023.

Phadke, Kishore D., Paul Goodyear, and Martin Bitzan, eds. Manual of Pediatric Nephrology. Springer, 2014.

Rees, Lesley, et al. Paediatric Nephrology. 3rd ed., Oxford University Press, 2019.

Warady, Bradley A., Franz Schaefer, and Steven R. Alexander, eds. Pediatric Dialysis. 3rd ed., Springer, 2022.

Webb, Nicholas J. A., and Robert J. Postlethwaite, eds. Clinical Paediatric Nephrology. 3rd ed., Oxford University Press, 2003.