What matters most is your ability to differentiate it as nutritional edema regardless of grading, such as in Kwashiorkor, versus edema from other medical causes like renal or cardiac conditions.

The key difference lies in avoiding diuretics and high-protein diets early in kwashiorkor, focusing on gradual nutritional rehabilitation.

To differentiate between edema caused by kwashiorkor and other medical conditions such as renal or cardiac disease, the following investigations, examinations, and historical details are helpful:

1.Medical History: 
  - Nutritional Deficiency: A history of insufficient protein intake, often in the context of an adequate calorie diet (like a diet based heavily on corn or rice), may indicate kwashiorkor.

  - Renal or Cardiac Indicators: Edema in the context of renal disease may follow a history of recent infections, such as pharyngitis in postinfectious glomerulonephritis, or massive proteinuria as seen in nephrotic syndrome. Cardiac causes may involve signs of heart failure like breathlessness, fatigue, or cyanosis 

2. Clinical Examination:
  - Kwashiorkor-Specific Signs: Bilateral pitting edema starting from the feet and progressing to the arms and face, shiny and peeling skin (“flaky paint”), sparse hair, distended abdomen with hepatomegaly, and a child appearing apathetic 

  - Signs of Cardiac or Renal Edema: Renal causes may show proteinuria, hypoalbuminemia, and hypertension. Cardiac causes often involve peripheral edema, ascites, and pulmonary edema with rales.

3. Laboratory Investigations:
  - Kwashiorkor: Marked hypoalbuminemia, hypoproteinemia, and possible deficiencies in vitamins and minerals. Urinalysis may show ketonuria but typically no proteinuria.

  - Renal or Cardiac Edema: In nephrotic syndrome, proteinuria (3-4+), hypoalbuminemia, and hypercholesterolemia are common. In cardiac failure, elevated BNP levels, and imaging (e.g., chest X-ray or echocardiogram) may show cardiomegaly and pulmonary congestion.