Lab findings/Diagnosis: The classic necessary finding in nephrotic syndrome is proteinuria (usually at least 3+ on urine dipstick, but a 24-hr urine protein of >3grams or a spot Urine Protein/Cr ratio >3 is more specific). Patients will also have hypoalbuminemia, dyslipidemia (LDL and TG), HTN and hypogammaglobulinemia. There is usually not as much inflammation as in patients with nephrotic syndromes, with some exceptions - but in most patients there will not be hematuria or dysmorphic RBCs/RBC casts. While pending biopsy, serologic workup can be performed (you'll see why below) including HIV, ANA, anti-DS DNA, Complement Levels, RPR, Hepatitis Panel and Serum Protein/Urine Protein Electrophoresis with IF. Remember to get a good review for all OTC medications taken as well. Workup in most adult patients will require a biopsy for ultimate diagnosis unless the cause is obvious (i.e. diabetic).
Clinical: Patients can present with HTN, Foamy Urine, Edema (starts in dependant areas - such as periorbital, scrotum and legs - but patients can eventually get anasarca/pleural effusion/ascites), infections (due to low gamma globulins), and thrombosis (Lower extremity, pulmonary embolism and renal ven thrombosis due to loss of AT-3). How does renal vein thrombosis present? -Acute abdominal pain + sterile pyuria should clue you in to this entity
Like the causes of glomerulonephritis, one can think of causes of nephrotic syndrome in two categories: Those that are systemic diseases, and those that cause more specific changes on biopsy
The systemic diseases that cause nephrotic syndrome:
1) Diabetes Mellitus - the most common! Remember the A1c can be normal in those patients that have developed some element of renal insufficiency. These patients usually do not need a renal biopsy to diagnose, and this is usually a clinical diagnosis. Patients should be placed on an ARB/ACEI and a low protein diet. Patients that do not have good glycemic control, uncontrolled HTN, and keep spilling protein will get progressive decrease in GFR. This is usually not too rapid, and occurs over a number of years.
2) SLE - Can also present with a more "nephritic" component. Remember, SLE can affect the kidney in a variety of ways...
3) Multiple Myeloma - Patients will present clinically with: high globulin gap, bone pain, anemia, renal failure, hypocalcemia. They might not have frank nephrotic syndrome on presentation, and might just has +1 protein in their urine. Still, a work-up for this must be done for patients with nephrotic syndrome (SPEP/UPEP with IF)
4) Amyloidosis - usually caused by light chain deposition, or from AL forms. On the boards, these patients will have other clues/findings (such as restrictive heart failure, neuropathy, etc)
The Renal "Causes" of nephrotic syndrome
1) Minimal Change Disease - In adults, the causes can be Idiopathic or caused by NSAIDS or Hodgkin's Lymphoma. Biopsy shows "effacement of foot processes" Treat with steroids +/- cytotoxic agents (such as cyclophosphamide)
2) Membranous Nephropathy - There are MULTIPLE causes for this on biopsy.
Drugs: NSAIDS, Gold
Autoimmune Disease: SLE
Cancer: Solid tumors, especially HCC, RCC, Colon and Lung
Infections (HCV, HBV, HIV, Malaria)
These patients usually have the underlying condition treated/removed first, and if
severe disease, get steroids +/- cytotoxic agents
3) Focal Segmental Glomerulosclerosis - has MULTIPLE causes as well
Idopathic (esp with h/o HTN), Sickle Cell Disease, Heroin use, Obesity.
Steroids are usually given to treat, but most end up needing Dialysis
Overall, patients with nephrotic syndrome should be placed on ACEI/ARB and diuretics as needed. Good BP control is essential. Many patients need to be on medications for dyslipidemia. A word about anticoagulation - these patients are "hypercoaguable", so do they all need treatment? Usually when inpatient - only DVT prophylaxis is given. Life-long treatment is usually given to patients with one thrombotic event. Prophylactic treatment to prevent an occurance of a thrombosis is not usually done, except in some cases of membranous nephropathy.
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