Differential Diagnosis
The patient's symptoms of abdominal pain, nausea, vomiting, increased frequency of urination, polydipsia, and weight loss, along with the physical examination findings and laboratory results, suggest a diagnosis related to metabolic and electrolyte imbalances. The presence of ketones and glucose in the urine is particularly telling.
Single most likely diagnosis
- Diabetic Ketoacidosis (DKA): This condition is characterized by hyperglycemia, metabolic acidosis, and ketosis, which aligns with the patient's symptoms and laboratory findings. The presence of ketones and glucose in the urine, along with the patient's lethargy, deep and labored breathing (Kussmaul breathing), and dry mucous membranes, strongly supports this diagnosis.
Other Likely diagnoses
- Dehydration: The patient's symptoms of dry mucous membranes, increased frequency of urination, and polydipsia suggest dehydration, which can be a contributing factor to her condition.
- Urinary Tract Infection (UTI): Although less likely given the overall clinical picture, a UTI could cause abdominal pain and increased frequency of urination.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Septic Shock: Although the patient's temperature is normal, septic shock can present with hypotension, tachycardia, and lethargy, making it a critical diagnosis not to miss.
- Acute Kidney Injury: The patient's increased frequency of urination and polydipsia could be indicative of kidney dysfunction, which would require prompt attention.
Rare diagnoses
- Other causes of ketoacidosis, such as alcoholic ketoacidosis or starvation ketoacidosis, although less likely in this patient given her age and presentation.
- Rare genetic disorders affecting glucose metabolism, such as maturity-onset diabetes of the young (MODY), which could present with similar symptoms but would be less common in this age group.
Given the patient's symptoms and laboratory findings, the most likely diagnosis is Diabetic Ketoacidosis (DKA), which would explain the presence of ketones and glucose in the urine, as well as the patient's metabolic acidosis and dehydration. Further evaluation would likely show decreased total body potassium (E) due to renal losses in the setting of DKA, and possibly increased arterial pCO2 (A) as a compensatory response to the metabolic acidosis, although the primary issue is the acidosis itself, which would more directly relate to decreased pH rather than increased pH (B). Excess water retention (C) is not typically seen in DKA, where dehydration is more common. Serum glucose concentration > 800 mg/dL (D) could be seen in DKA but is not the most direct consequence of the condition described.