We have previously discussed several kidney related issues: Hypertension Crisis, Kidney Stones, HSP, Rhabdomyolysis and Proteinuria. Wanting to remain vigilant for the big, bad, and ugly conditions that may be lurking, let us explore another renal related condition: Nephrotic Syndrome.
Nephrotic Syndrome Basics
- One of the more common childhood kidney disorders.
- Characterized by:
- Heavy proteinuria (>1 gram/meter squared/Day, Urine Pro/Cr > 2)
- Hypoalbuminemia (<2.5 g/dL)
- Hyperlipidemia (cholesterol >200 mg/dL)
- Primary (aka, idiopathic) – accounts for >90% of cases
- Secondary – can be due to a large variety of conditions, like:
- Systemic Lupus
- IgA Nephropathy
- HIV infection
- Histologic Classifications
- Minimal Change (>77%)
- Focal Segmental Glomerulosclerosis (~8%)
- Membranoproliferative Glomerulonephritis (~6%)
Why Losing Protein Matters
- Losing protein and protein-bound molecules lead to several complications.
- It is these potential complications that need to be kept in mind.
Compromised Immune Function
- Infection is a common complication and cause of mortality!
- Immunoglobulins are lost, leading to low IgG levels.
- Prone to serious bacterial infections
- Steptococcus pneumoniae
- Escherichia coli
- Hemophilus bacteria
- Gram Negatives
- Spontaneous Bacterial Peritonitis, Bacteremia, and Cellulitis are most common.
- Fever needs to be respected and often empiric antibiotics while awaiting cultures is warranted.
- Think of spontaneous bacterial peritonitis in patient with fever and abdominal pain.
- 2-9% of children with nephrotic syndrome will develop clots.
- Imbalance between anticoagulants and procoagulants.
- Urinary losses of anticoagulants (antithrombin III, plasminogen, Protein S)
- Increased procoagulants (fibrinogen, Factor VIII, plasminogen activity factor-1)
- Procoagulant state can be further exacerbated by hypovolemia.
- These children are encouraged to avoid prolonged bed rest.
Abnormal Lipid Metabolism
- Adults with Nephrotic Syndrome have an increased risk of coronary artery disease.
- Unclear if the same is true for children.
- Patients have increased LDL, increased lipoproteins, and hypertriglyceridemia.
- Transferrin and Erythropoietin are lost.
- Both can lead to microcytic anemia.
Low 25-hydroxy-Vitamin D levels
- Loss of Vitamin D binding protein.
- Decreased serum Calcium levels can occur and hyperparathyroidism may develop.
- May develop osteitis fibrosis and osteomalacia.
What the Nephrologist May Ask You to Order
- The evaluation of proteinuria can usually be done as an outpatient.
- In some cases it may be more helpful to start the work-up now, in which case your Nephrologist may as you to obtain:
- Urinalysis (send home with specimen cup for first morning urine for Pro/Cr ratio too)
- Electrolytes with BUN/Cr
- Cholesterol level
- Albumin level
- Tuberculin test
- Hep B, Hep C, HIV serology
- Complement 3 level + ASO titre
- ANA (if you suspect Lupus)
So, while most of this condition’s work-up and management occurs in the outpatient realm, the potential complications, especially serious bacterial infections and thromboembolism, may make the patient present to your ED. So it is best to be vigilant and prepared.