Lissaur_nefrologie

7/30/2019 Lissaur_nefrologie

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Ch. 18 kidney and urinary tract disorders.

Proteinuria.Persistent proteinuria is significant and should be quantified by measuring the urineprotein/creatinine ratio in an early morning sample (protein should not exceed

20mg/mmol of creatinine). A common cause is orthostatic (postural) proteinuria, whereproteinuria is only found when the child is upright. It can be diagnosed by measuring theurine protein in a series of morning urine specimens. Prognosis is excellent.

Nephrotic syndrome.Heavy proteinuria results in a low plasma albumin, and oedema. Clinical signs are:- Periorbital oedema;- scrotal or vulval , leg and ankle oedema;- Ascites;- Breathlessness due to pleural effusions.

In 85-90% of children the proteinuria resolves with corticosteroid therapy. These childrendo not progress to renal failure. The most widely used protocol is to initially give oral

corticosteroids. The median time for the urine to become free of protein is 11 days.Children who do not respond to 4-8 weeks of corticoid therapy or have atypical featuresmay have a more complex diagnosis and require a renal biopsy. The child is susceptibleto several serious complications:- Hypovolemia: during the initial phase of oedema they become volume depleted. Thechild characteristically complains of abdominal pain and may feel faint. There isperipheral vasoconstriction and urinary sodium retention. It requires urgent treatmentwith intravenous albumin as the child is at risk of vascular thrombosis and shock.- Thrombosis: a hypercoagulable state, due to urinary losses of antithrombin, which maybe exacerbated by steroid therapy.- Infection: children in relapse are at risk of infection with capsulated bacteria, especiallypneumococcus.- Hypercholesterolaemia: this correlates inversely with the serum albumin.

Congenital nephrotic syndrom.Presents in the first 3 moths of life. It is rare. It is associated with a high mortality, usuallydue to complications of hypoalbuminaemia rather than renal failure.

Heamaturia.Urine is red in colour or tests positive for haemoglobin on urine sticks should be examinedunder the microscope to confirm haematuria. Glomerular haematuria is suggested bybrown urine, the presence of deformed red cells and casts, and is often accompanied byproteinuria. Lower urinary tract haematuria is usually red, occurs at the beginning or endof the urinary stream, is not accompanied by proteinuria and is unusual in children.Urinary tract infection is the most common cause. A renal biopsy may be indicated if:- Significant persistent proteinuria;- Recurrent macroscopic heamaturia;- Renal function is abnormal.

Acute nephritis.Restricts glomerular blood flow and therefore filtration is decreased. This leads to:- Decreased urine output and volume overload;- Hypertension;- Oedema;- Haematuria and proteinuria.

Post-streptococcal and post-infectious nephritis: follows a streptococcal sore throat orskin infection and is diagnosed by evidence of a recent streptococcal infection and low

complement C3 levels that return to normal after 3-4 weeks.

Henoch-Schonlein purpura: combination of the following features,


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- Characteristic skin rash;- Arthralgia;- Periarticular oedema;- Abdominal pain;- Glomerulonephritis.It occurs between the ages of 3-10 years, peaks during winter. The IgA and IgG interact to

produce complexes that activate complement and are deposited in affected organs. Theaffected children often have a fever. The rash is the most obvious feature. It issymmetrically distributed over the buttocks, the extensor surfaces of the arms and legs,and the ankles. Joint paint occurs in 2/3 of patients. There is periarticular oedema. Colickyabdominal pain occurs in many children and if severe can be treated with corticosteroids.Renal involvement is common, but it is rarely the first symptom. Over 80% havemicroscopic or macroscopic heamaturia or mild proteinuria. Risk factors for progressiverenal disease are heavy proteinuria, oedema, hypertension and deteriorating renalfunction.

Vasculatitis: commonest vasculitis to involve the kidney is Henoch-schonlein purpura.However, renal involvement may occur in rare vasculitides such as polyarteritis nodosa,microscopic polyarteritis and wegener granulomatosis. Characteristic symptoms are

fever, malaise, weight loss, skin rash and arthropathy.

Systemic lupus erythematosus (SLE): presents mainly in adolescent girls and youngwomen. It is characterised by the presence of multiple autoantibodies, includingantibodies to double stranded DNA. The C3 and C4 components of complement may below. Heamaturia and proteinuria are indications for renal biopsy.

Hypertension.Blood pressure needs to be measured with a cuff over 2/3 the length of the upper arm.Symptomatic hypertension in children is usually secondary to renal, cardiac or endocrinecauses. Presentation includes vomiting, headaches, facial palsy, hypertensiveretinopathy, convulsions or proteinuria. Early detection is important.

Renal:- Renal parenchymal disease;- Renovascular, e.g. renal artery stenosis;- Polycystic kidney disease;Coarctation of the aorta.Catecholamine excess:- Phaeochromocytoma;- Neuroblastoma;Endocrine:- Congenital adrenal hyperplasia;- Cushing syndromeEssential hypertension.

Renal masses.Bilaterally enlarged kidneys in early life are most frequently due to autosomal recessivepolycystic kidney disease, which is associated with hypertension, hepatic fibrosis andprogression to chronic renal failure. This form must be distinguished from the autosomaldominant adult-type polycystic kidney disease.

Renal calculi.Renal stones are uncommon in childhood, predisposing causes must be sought:- Urinary tract infection;- Structural anomalies of the urinary tract;- Metabolic abnormalities.Commonest are phosphate stones associated with infection. Calcium-containing stones

occur in idiopathic hypercalciuria.

Stones that are not passed spontaneously should be removed, by either lithortipsy or


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surgery, and any predisposing structural anomaly repaired.

Renal tubular disorders.

General proximal tubular dysfunction (fanconi syndrome).Proximal tubule cells are among the most metabolically active in the body, especially

vulnerable to cellular damage. Fanconi syndrome should be considred in a child presentwith:- Polydipsia and polyuria;- Salt depletion and dehydration;- Hyperchloraemic metabolic acidosis;- Rickets;- Failure to thrive/poor growth.

Acute kidney injury.There is sudden, potentially reversible, reduction in renal function. Oliguria (


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Many children have had their renal disease detected before birth by antenatal ultrasound.The aims are to prevent the symptoms and metabolic abnormalities of chronic renalfailure, to allow normal growth and development.

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