In a 20-year-old patient with a history of gastric sleeve presenting with one week of dizziness, no red flags, and hypotension (BP 90/55), what initial investigations should be ordered?

Initial Laboratory and Diagnostic Workup

In a 20-year-old post-gastric sleeve patient presenting with one week of dizziness and hypotension (BP 90/55), order a complete metabolic panel (including electrolytes, glucose, creatinine), complete blood count, orthostatic vital signs, ECG, and consider cortisol/ACTH levels given the concerning combination of symptoms and surgical history.

Immediate Bedside Assessment

Start with orthostatic vital signs - measure BP and heart rate supine, then after standing for 1-3 minutes. A drop of ≥20 mmHg systolic or ≥10 mmHg diastolic confirms orthostatic hypotension and suggests volume depletion, autonomic dysfunction, or endocrine abnormality 1, 2. This is critical because it distinguishes between true hypotension requiring intervention versus positional symptoms that may be managed conservatively.

Essential Laboratory Tests

First-Line Blood Work (Order Immediately):

• Complete Metabolic Panel: Focus on sodium, potassium, glucose, and creatinine 3

  • Hyponatremia and hyperkalemia suggest adrenal insufficiency
  • Hypoglycemia can occur post-bariatric surgery from multiple mechanisms 4
  • Renal function assessment is essential given hypotension duration

• Complete Blood Count: Rule out anemia from nutritional deficiencies or occult bleeding 3

• Thyroid-Stimulating Hormone (TSH): Hypothyroidism can cause fatigue and contribute to hypotension 3

Critical Consideration - Adrenal Insufficiency:

Given the post-gastric sleeve history combined with persistent hypotension and dizziness, strongly consider ordering morning cortisol and ACTH levels 5. This 20-year-old patient fits the profile for autoimmune adrenal insufficiency, which can present insidiously with:

• Orthostatic hypotension
• Dizziness and fatigue
• Weight loss (may be attributed to surgery)
• Potential hyperpigmentation (check skin folds, surgical scars)

The case report 5 of a 19-year-old with similar presentation (dizziness, orthostatic hypotension, initially attributed to gastroenteritis) who deteriorated and was ultimately diagnosed with primary adrenal insufficiency is directly relevant here.

Cardiovascular Assessment

• 12-Lead ECG: Essential to exclude arrhythmias, conduction abnormalities, or signs of structural heart disease that could cause hypotension 3
• Heart rate measurement over 30 seconds: Inappropriate tachycardia or bradycardia provides diagnostic clues 6

Post-Bariatric Surgery Specific Considerations

Nutritional Deficiencies to Screen:

• Thiamine (Vitamin B1): Deficiency can cause Wernicke's encephalopathy presenting with dizziness, gait instability, and altered mental status 7
• Vitamin B12 and folate: Anemia and neurological symptoms
• Iron studies: Microcytic anemia common post-sleeve gastrectomy

Volume Status Assessment:

Post-bariatric patients are at risk for:

• Dehydration from reduced oral intake, malabsorption, or inadequate fluid replacement
• Electrolyte abnormalities from vomiting, diarrhea, or diuretic use
• Check for signs of volume depletion: dry mucous membranes, decreased skin turgor, concentrated urine

What NOT to Order Initially

Avoid extensive imaging (CT abdomen/pelvis, echocardiography) unless the basic workup suggests specific pathology or the patient has red flag symptoms (chest pain, severe abdominal pain, neurological deficits beyond dizziness) 8. The evidence does not support routine advanced imaging for uncomplicated dizziness and hypotension.

Clinical Pitfalls to Avoid

1. Don't dismiss hypotension as "normal for this patient" - BP 90/55 in a 20-year-old warrants investigation, especially with symptoms
2. Don't attribute all symptoms to the bariatric surgery - while nutritional deficiencies are common, life-threatening conditions like adrenal insufficiency must be excluded 5
3. Don't delay cortisol testing if clinical suspicion exists - waiting for deterioration (as occurred in the case report 5) risks adrenal crisis
4. Don't forget to ask about medication use - NSAIDs, supplements, or other substances can affect BP 6, 3

Diagnostic Algorithm Summary

1. Orthostatic vital signs (immediate)
2. Basic labs: CMP, CBC, TSH (stat)
3. ECG (within hours)
4. If orthostatic hypotension confirmed + concerning features:
   → Add morning cortisol/ACTH
   → Consider thiamine level
   → Check vitamin B12, folate, iron studies
5. Reassess within 24-48 hours based on results

The key is recognizing that post-bariatric surgery patients have unique vulnerabilities (nutritional deficiencies, malabsorption, hormonal changes) that require targeted investigation beyond standard hypotension workup 4, 7.