Differentials
Dehydration
SIGNS / SYMPTOMS
Total body water is depleted, without equivalent reduction in solutes. Patients with pure dehydration usually have relatively fewer signs of intravascular depletion and relatively more signs of intracellular fluid losses (e.g., decreased skin turgor, dry mucous membranes, sunken eyes).
INVESTIGATIONS
Dehydration is nearly always accompanied by some degree of volume depletion, and test abnormalities overlap significantly with those of volume depletion. Despite significant overlap, the distinction is important in directing therapies and monitoring for complications.
In isolated dehydration, serum sodium is high.
Acute glomerulonephritis
SIGNS / SYMPTOMS
Hypertension is usually present.
Clinical indicators of fluid retention are present despite decreased urine output.
Cola-colored urine is classically described in acute glomerulonephritis.
INVESTIGATIONS
Urine sediment has blood, casts, proteinuria, and other abnormalities.
BUN and serum creatinine both elevated.
Adrenal insufficiency
SIGNS / SYMPTOMS
Onset of symptoms is generally extremely gradual.
Deficiencies of ≥1 of the 3 groups of adrenal steroid hormones can coexist and in many cases are similar to findings of volume depletion (i.e., fatigue, vomiting, hypotension).
In cases of adrenal androgen deficiency, hyperpigmentation may be notable on mucous membranes, extensor surfaces, and palms.
INVESTIGATIONS
Hyperkalemia, hyponatremia, normal anion gap, and metabolic acidosis are classically seen.
ECG may show signs of hyperkalemia.
Serum cortisol may be low, but cortisol is always inappropriately low under conditions of stress.
Intussusception or volvulus
SIGNS / SYMPTOMS
Significant abdominal tenderness. Bilious emesis may occur in volvulus. Passage of mucus and bloody stool (currant-jelly stool) are classically described in intussusception.
A sausage-shaped mass may be palpable and is highly suggestive of intussusceptions.
INVESTIGATIONS
Abdominal ultrasound or abdominal CT scan may show obstructive pattern with dilated loops of bowel with air-fluid levels or bulls-eye like appearance of intussuscepted intestine within the lumen of the intestine.[26]
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