Nephrotic syndrome

Published on 02/04/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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227 Nephrotic syndrome

Instruction

Look at this patient.

Salient features

History

• History of diabetes (N Engl J Med 1998;338:1202–11)

• Hypertension

• History of acute glomerulonephritis, streptococcal sore throat

• Medications: NSAIDs, captopril, street heroin, gold, pencillamine, lithium, chlorpropamide, rifampin, tolbutamide

• History of SLE, vasculitides, amyloidosis

• Neoplasms: Hodgkin’s and other lymphoma, solid tumours

• Familial history: sickle cell disease, partial lipodystrophy (p. 611), Alports syndrome

• Parasites: malaria, toxoplasmosis, schistosomiasis.

Examination

• Generalized oedema: puffiness of face, pitting oedema of legs and hands

• Look at the nails for ridges of hypoproteinaemia

• Comment on the pallor

• Tell the examiner that you would like to examine:

• the abdomen for ascites
• the urine for protein and sugar.

Note: Urine microscopy may show oval fat bodies, which consist of degenerating tubular epithelial cells having cholesteryl esters; these appear as ‘grape clusters’ with light microscopy and have a ‘Maltese-cross’ appearance under polarized light.

Diagnosis

This patient has nephrotic syndrome (lesion) caused by diabetes mellitus (aetiology), and has developed gross anasarca indicating hypoalbuminaemia and marked urinary protein loss (functional status).

Questions

What do you understand by the term nephrotic syndrome?

It consists of albuminuria (>3.5 g/day) and hypoalbuminaemia accompanied by generalized oedema, hyperlipidaemia (caused by increased hepatic production) and lipiduria.

What causes this syndrome?

• Glomerular disease: minimal change glomerulonephritis, membranous glomerulonephritis, proliferative glomerulonephritis.

• Systemic disease: diabetes mellitus, SLE, amyloidosis, drugs (captopril, gold, penicillamine, street heroin), Hodgkin’s disease, syphilis, malaria, HIV, cancer, hepatitis B, multiple myeloma, renal primary (AL) amyloidosis.

How would you investigate these patients?

• Creatinine clearance, 24-hour urinary protein, urine electrophoresis

• FBC, ESR

• Urea and electrolytes, serum creatinine, albumin

• Serum cholesterol (dyslipidaemia is caused by both overproduction and impaired catabolism of apolipoprotein B-containing lipoproteins)

• DNA antibody, anti-nuclear factor, complement levels

• Renal biopsy.

What complications may such a patient suffer?

• Thromboembolic events, including renal vein thrombosis and deep vein thrombosis (caused by loss of antithrombin III and other proteins involved in the coagulation and fibrinolytic cascade)

• Protein malnutrition

• Acclerated atherosclerosis

• Infection.

Advanced-level questions

What is orthostatic proteinuria?

It is usually seen in adolescents and occurs when standing and resolves on lying down. The long-term prognosis is good.

What do you know about Tamm–Horsfall protein in the urine?

Normal individuals excrete <150 mg/day protein. Of this, about 5–15 mg is albumin and the remainder consists of different plasma proteins and glycoproteins derived from renal cells. Tamm–Horsfall mucoprotein is the most abundant protein that is not derived from plasma but from the cells of the ascending limb of the loop of Henle; it is excreted at the rate of 50–75 mg/day. Pathological proteinuria occurs when daily excretion exceeds 150 mg protein.

What is the treatment of patients with nephrotic syndrome?

• Diuresis: furosemide (acts in the ascending thick loop of Henle) with thiazides (reduce sodium absorption in the distal nephron) and potassium-sparing diuretics

• Prevention of thromboemboli: heparin, anticoagulants and support stockings when patients have nephrotic proteinuria, an albumin level <20 g/l or both

• Infusion of hyperoncotic albumin should only be tried if symptomatic hypovolaemia is present

• Plasma ultrafiltration in severe cases

• Renal ablation by bilateral nephrectomy or embolization of the renal artery may be indicated to avoid serious risks of severe hypoproteinaemia and hypovolaemia

• Pneumococcal vaccine

• ACE inhibitors or angiotensin receptor blockers is indicated even in normotensive patients to reduce proteinuria

• Colchine in familial Mediterranean fever

• Interferon-alfa in hepatitis B-associated nephrotic syndrome, hepatitis-C associated membranoproliferative glomerulonephritis and cryoglobulinaemia

• Prednisone, 8-week course, in minimal change nephropathy.

Nephrotic syndrome was clearly described by R Bright (1789–1858), an English physician. He qualified from Edinburgh and worked at Guy’s Hospital, London. Chronic nephritis is known as Bright’s disease. Three of his renal specimens are still preserved at Guy’s Hospital.

I Tamm, scientist, Rockefeller University, New York.

FL Horsfall, Professor of Microbiology, Sloan Kettering Institute and Cornell University, New York.

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