Differential Diagnosis for a 15-month-old with Vomiting, Lethargy, and Increased Urination
Single most likely diagnosis:
- Diabetic Ketoacidosis (DKA): The symptoms of vomiting, lethargy, tachypnea, decreased appetite, irritability, increased urination, and increased thirst are classic for DKA, especially in a pediatric patient. The absence of diarrhea and the presence of increased urination and thirst are particularly suggestive of a metabolic disorder like diabetes.
Other Likely diagnoses:
- Gastroenteritis: Although there's no diarrhea, some cases of gastroenteritis can present with vomiting alone, and the lethargy and irritability could be due to dehydration.
- Urinary Tract Infection (UTI): UTIs can cause systemic symptoms like fever, lethargy, and irritability in young children, along with increased urination.
- Pyloric Stenosis: This condition, which causes gastric outlet obstruction, can lead to projectile vomiting, but it typically doesn't cause increased urination or thirst.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Meningitis or Sepsis: These conditions can present with non-specific symptoms like lethargy, irritability, and vomiting in young children. They are medical emergencies requiring prompt diagnosis and treatment.
- Intussusception: Although more commonly associated with abdominal pain and bloody stools, intussusception can sometimes present with vomiting and lethargy.
- Adrenal Insufficiency: This rare condition can cause vomiting, lethargy, and dehydration, similar to DKA, and is critical to diagnose due to its high mortality if untreated.
Rare diagnoses:
- Congenital Adrenal Hyperplasia: This group of genetic disorders can lead to adrenal insufficiency and sometimes presents with symptoms similar to DKA.
- Hyperthyroidism: Although rare in children, hyperthyroidism can cause increased urination, thirst, and vomiting, among other symptoms.
- Renal Tubular Acidosis: A rare condition affecting the kidneys' ability to regulate acid levels, which can lead to symptoms like vomiting and increased urination.