What are the causes of kidney disease in children?
Urinary tract infection (UTI), proteinuria and/or hematuria, nephrotic syndrome, glomerulonephritis, are the commonly seen kidney diseases in children. Hydronephrosis (dilated renal pelvis) is sometimes diagnosed in new born baby with the use of antenatal ultrasound examination. Often it is benign and requires no intervention. Acute or chronic renal failure, though uncommon, are important. From time to time, cases of renal cysts and hereditary kidney diseases are seen.
(Fig. 1) frothy urine due to presence of protein in it
(Fig. 2.a) renal cyst - appearance under ultrasound
(Fig. 2.b) renal cyst - cysts over the surface of kidneys in polycystic kidney disease
(Fig. 3) nephrotic syndrome - swollen child
Urinary tract infection (UTI)
UTI occurs when there is bacterial growth in the urinary system. The children with UTI may present with painful micturition and may have to go to toilet to urinate frequently. The urine may turn turbid (large number of white blood cells) and even red in colour (large number of red blood cells). There may also be loin (middle part of the back lateral to the muscle column) pain. Fever is common in young children and may be the only symptom. A high index of suspicion is needed in young child to diagnose UTI. Antibiotic treatment is needed and further evaluation of presence of any structural abnormality of the urinary tract by imaging may be necessary. Untreated, UTI may lead to renal damage and scarring and may result in hypertension or kidney failure in the long-term.
(Fig. 4) white blood cell under microscopy
Abnormal Urinalysis
Abnormal urinalysis in the form of proteinuria or hematuria is usually found incidentally during medical consultation for other problems or during population screening as in some Asian countries such as Japan, Korea. Proteinuria means the presence of excess amount of protein in the urine. Often, it is related to an upstanding posture and in this case, it is regarded as a benign condition. Hematuria means the presence of excess amount of red blood cells in the urine. It can be due to bleeding from any where along the urinary tract from the glomerulus to the urethral opening. It can also be due to contamination from nearby skin abrasion or from menstrual blood in girls. Causes of proteinuria or hematuria have to be elucidated and treated accordingly.
(Fig. 5.a) RBCs in urine - Red urine (gross hematuria)
(Fig. 5.b) RBCs in urine - detected by stix test with change of stix colour
(Fig. 5.c) RBCs in urine - under microscopy
Nephrotic Syndrome
Nephrotic syndrome is diagnosed when there is generalized edema (swelling) of the child (such as puffy face, abdominal swelling and leg swelling) (Fig. 3) together with loss of large amount of protein in the urine (Fig. 1) resulting in low albumen level and elevated lipid level in the blood. Majority are due to idiopathic cause. Most of them respond to a course of steroid treatment. Small % are resistant to steroid treatment and are required to undergo kidney biopsy to evaluate the microscopic changes occurring in the kidney to guide further drug therapy. A few resistant cases may progress to renal failure.
Glomerulonephritis (GN)
Glomerulonephritis (GN) (inflammation of the kidneys) is commonly due to streptococcal infection in the throat (sore throat) or on the skin (skin infection) occurring 2-3 weeks ago. This may result in acute renal (kidney) failure with no or much decrease in urine output which often appear smoky. The child may present with puffy face, ankle swelling and even shortness of breath (all related to water retention secondary to inability of the failed kidneys to excrete ingested water). GN can also be due to systemic lupus erythematosus (SLE) (Fig. 6), Henoch-Scholein purpura (HSP) (Fig. 7), IgA nephropathy and other less common causes. SLE though can not be cured presently, can be controlled with drugs. HSP is a form of blood vessel inflammatory disease. It often involves the kidneys though severe kidney damage in the form of nephrotic syndrome, nephritis or renal failure is not common. IgA nephropathy is said to be the most common GN worldwide in adults. It can only be diagnosed with renal biopsy.
(Fig. 6) butterfly rash over face in SLE
(Fig. 7.a) HSP - rash over lower limb
(Fig. 7.b) HSP - rash over buttock (both not blench on pressure and raised)
Acute renal failure (ARF)
Acute renal failure (ARF) means the cessation of kidney function abruptly with little or no urine passed causing fluid retention presented with puffy face, abdominal swelling or even shortness of breath due to pulmonary edema (fluid inside lung substance). It can be caused by any type of GN though post-streptoccal GN being the commonest. It can also caused by obstruction of the urinary tract. In developing countries where infective diarrhoea (gastroenteritis) is common, ARF can be caused by hypovolumia secondary to severe dehydration due to diarrhoea. In obstructive cases, relief of obstruction is usually curative. In others, conservative management will usually suffice with return of renal function gradually. In severe cases, rarely, dialysis may be required.
