Diagnostic Testing for Acute Stomach Discomfort, Body Aches, Nausea, and Headache with Negative COVID-19 and Influenza Tests
Despite negative COVID-19 and influenza tests, you should order basic laboratory testing including complete blood count, basic metabolic panel, C-reactive protein, liver function tests (AST, ALT, bilirubin), and consider repeat COVID-19 testing if clinical suspicion remains high, as false-negative results can occur early in infection.
Initial Laboratory Panel
Order the following basic laboratory tests to evaluate for systemic inflammation and organ involvement:
- Complete blood count (CBC) to assess for lymphopenia, neutrophilia, or thrombocytopenia 1
- Basic metabolic panel to evaluate electrolyte disturbances and renal function 1
- C-reactive protein (CRP) as a marker of inflammation 1
- Liver function tests including AST, ALT, and bilirubin, as abnormal liver enzymes occur in 15-17% of patients with viral illnesses including COVID-19 1
- Erythrocyte sedimentation rate (ESR) as an additional inflammatory marker 1
Considerations for Repeat COVID-19 Testing
Even with an initial negative test, repeat testing may be warranted based on several factors:
- Timing matters: False-negative RT-PCR results can occur early in infection due to the time-window of viral replication 1
- Nasopharyngeal samples are superior to oropharyngeal samples in the early disease stage 1
- GI symptoms can precede typical COVID-19 symptoms by several days, and your patient's constellation of stomach discomfort, nausea, body aches, and headache fits this pattern 1
- Consider repeat nasopharyngeal RT-PCR if clinical suspicion remains high despite initial negative result 1
The AGA Institute specifically recommends monitoring patients with new-onset GI symptoms for development of COVID-19, as these symptoms may appear before respiratory manifestations 1.
Additional Testing Based on Symptom Severity
If the patient appears more systemically ill, consider:
- Procalcitonin to help differentiate bacterial from viral causes 1
- Ferritin as an inflammatory marker 1
- D-dimer if there are concerns about thrombotic complications 1
- Lactate dehydrogenase (LDH) as another marker of tissue damage 1
- Troponin if there are any cardiac symptoms or concerns 1
Imaging Considerations
While not first-line for this presentation, chest imaging may be considered:
- Chest X-ray can serve as an initial screening tool if respiratory symptoms develop or if there's high clinical suspicion for COVID-19 despite negative testing 1
- Chest CT is more sensitive than X-ray and may be useful in patients with high clinical suspicion but negative RT-PCR, though this is typically reserved for more severe presentations 1
Clinical Pitfalls to Avoid
Do not assume a single negative COVID-19 test definitively excludes infection, especially when symptoms align with viral illness patterns. The sensitivity of RT-PCR varies with timing of specimen collection and viral load 1, 2.
Do not overlook the possibility of post-acute sequelae if symptoms persist beyond typical acute viral illness duration, as chronic GI symptoms can develop following COVID-19 3.
Do not forget that coinfection with multiple pathogens is possible, though rare (0.54% in one series), and can complicate the clinical picture 4.
Algorithmic Approach
- Order basic labs immediately: CBC, BMP, CRP, LFTs (AST, ALT, bilirubin) 1
- If inflammatory markers are elevated (CRP, ESR): Add ferritin, procalcitonin, D-dimer, LDH 1
- If GI symptoms predominate and persist: Consider repeat COVID-19 RT-PCR testing within 24-48 hours 1
- If cardiac symptoms emerge: Add troponin and ECG 1
- If respiratory symptoms develop: Obtain chest X-ray 1
The combination of stomach discomfort, nausea, body aches, and headache represents a nonspecific viral syndrome that warrants systematic laboratory evaluation to identify the underlying cause and assess disease severity, even when initial viral testing is negative 1.