Uncategorized – Pinto Pearls

When Symptoms Are Subtle – The Clinical Value of CRP

Dr. Fiona Pinto — Tue, 12 Aug 2025 20:57:41 +0000

Hey all,

We’ve all seen them—the patients who don’t look sick, until they suddenly are. Their vitals lull us into false reassurance. Their white count lies. But sometimes, CRP knows first

Case #1: “Cough”

45M, previously well, coming in with 3-day dry cough and fatigue, but looks well
Vitals: T 37.8°C, HR 88, BP 128/78, RR 16, O₂ sat 97% RA
WBC: 9.2
CXR: Normal
CRP: 121 mg/L

He looks great and has normal vitals, normal WBC

What do you do?

Case #2: “Abdominal Pain”

31M, no significant PMHx with a chief complaint of vague right lower quadrant pain
Vitals: T 37.5°C, HR 92, BP 125/82, RR 16
WBC: 10.1
Abdo exam: Soft, minimal tenderness
CRP: 132 mg/L

Normal Vitals, Normal WBC, Exam Underwhelming.

What do you do?

Case #3: “Limping Child”

4F, previously well brought in by her parents because she refuses to bear weight on left leg and decreased range of motion of her hip. She does have a history of a viral cough for the past 3 days
Vitals: T 37.2°C, HR 105, BP 96/60
WBC: 12.4
X-ray hip/femur: Normal
CRP: 89mg/L

She looks well. Maybe just transient synovitis?

What do you do?

Case #4: “Back Pain”

45F, female presents with vague symptoms of low back pain for 2 days. She has a history of drug use but is not clear whether she uses IV drugs.
Vitals: T 37.2°C, HR 85, BP 130/80
WBC: 11.9
L-spine/ Pelvic xrays: Normal
CRP: 98mg/L

Exam: She has no point tenderness, though is quite uncooperative. Ambulates in ED

What do you do?

Answers

Case 1: You nearly discharge him as “viral bronchitis.” But that CRP! Why is it elevated? You push for a chest CT—multifocal pneumonia. Early pneumonia, caught in time. Whew!

Case 2: You aren’t sure he needs imaging. But that CRP seems too high to ignore, so you do a CT. CT confirms perforated appendicitis with small pelvic fluid collection.

Case 3: She looks well, but the labs say otherwise. A joint aspiration is done and confirms septic arthritis. She’s in the OR that night!

Case 4: It seems like non-specific back pain, but you push for an MRI: spinal epidural abscess.

Ok Doc, So, What Exactly Is CRP?

C-reactive protein (CRP) is an acute-phase reactant produced by the liver in response to inflammation.

So, What Is CRP Telling Me?

CRP reflects inflammation—especially bacterial.
It rises quickly (within 6–8 hours) and can peak within 48 hours of an inflammatory stimulus.
It falls with treatment, so it’s also helpful for monitoring trends in admitted patients.
It won’t tell you where the problem is—but it tells you there is a problem, often before other tests do.

Ok, What Do the Numbers Mean?

When Does CRP Help in the ED?

When everything looks “okay”
- Normal vitals, reassuring WBC, and no fever don’t rule out bacterial infection—especially in the elderly, immunocompromised, or infants.
- CRP >100 mg/L should trigger a deeper search for source.
When imaging is negative or borderline
- Negative CXR in early pneumonia?
- Benign abdomen with vague pain?
- Limping child with normal x-ray?
- CRP doesn’t diagnose, but it keeps you from missing the forest for the trees.
When you’re deciding about discharge
- A CRP <20 mg/L in a well-appearing, afebrile patient can support discharge, especially when your gut says “probably viral.”
- A CRP >100 mg/L with no clear source? You need to dig—or keep them.

Ok Doc, but how do I Actually Use CRP in Practice

Undifferentiated Fever
- CRP <20 mg/L: Likely viral, often no antibiotics needed.
- CRP >100 mg/L: Likely bacterial—consider empiric antibiotics and search for source.
Sepsis Evaluation
- Use CRP alongside lactate, vitals, and WBC to assess severity.
- CRP >200–300 mg/L often signals severe infection.
- Serial CRPs help track response after source control.
Respiratory Infections
- CRP <20 mg/L: Likely viral—hold antibiotics.
- CRP >100 mg/L: Likely bacterial—even if CXR is borderline.
- CRP 20–100 mg/L: Use clinical judgment and have follow up
Abdominal Pain & Possible Surgical Abdomen
- Appendicitis: CRP >50 mg/L supports the diagnosis.
- Diverticulitis: High CRP with localized tenderness is suggestive.
- Ischemia or perforation: CRP >150–200 mg/L raises suspicion.
Pediatric Fever Without Source (≥ 3 months)
- CRP >40–60 mg/L increases concern for serious bacterial infection, especially with abnormal WBC or PCT.
Back Pain
- Elevated CRP points to an infectious cause

Pitfalls to Avoid

Don’t delay antibiotics in septic patients just to wait for a CRP.
CRP can lag—may still be normal if symptoms <6 hours.
It’s non-specific—can rise in trauma, autoimmune disease, cancer, or surgery.
Low CRP ≠ Normal. Early disease can still have low CRP.

Summary Table

CRP Summary Table

Take Home Points

CRP >100 but normal exam? Don’t discharge without knowing why it’s high.
CRP <20? If everything else looks viral, it probably is.
In vague cases—especially elderly or pediatric—CRP can be the only early red flag.
Always interpret CRP in clinical context. It’s not the answer—but it nudges you toward it.

References

Aabenhus, Rune, et al. “Biomarkers as Point-of-Care Tests to Guide Prescribing of Antibiotics in Patients with Acute Respiratory Infections in Primary Care.” Cochrane Database of Systematic Reviews, no. 11, 2024, CD010130.

Froom, Paul, and Margalit Shimoni. “C-Reactive Protein.” Clinical Biochemistry, vol. 49, no. 4–5, Mar. 2016, pp. 291–292.

Pepys, Mark B., and Gideon M. Hirschfield. “C-Reactive Protein: A Critical Update.” The Journal of Clinical Investigation, vol. 111, no. 12, June 2003, pp. 1805–1812.

Sproston, Nicola R., and Jeremy J. Ashworth. “Role of C-Reactive Protein at Sites of Inflammation and Infection.” Frontiers in Immunology, vol. 9, 18 May 2018, p. 754.

Uzzan, Boris, et al. “Procalcitonin and C-Reactive Protein as Prognostic Markers of Sepsis.” Critical Care Medicine, vol. 51, no. 3, 2023, pp. 356–365.

Virk, Ajit, and Jonathan M. W. Chan. “C-Reactive Protein as a Biomarker of Bacterial Infection.” British Journal of Hospital Medicine, vol. 78, no. 7, July 2017, pp. 399–402.

When Gastro Isnt Just Gastro

Dr. Fiona Pinto — Mon, 13 Jan 2025 21:31:19 +0000

When Gastro Isn’t Just Gastro!

A Deeper Dive into Nausea and Vomiting

Welcome to the very first edition of 2025—let’s kick off the year with a fresh approach!

Winter is here, and along with it, the usual wave of viral illnesses. But today, we’re doing something
exciting and interactive! Get ready to dive into a series of intriguing case presentations and put
your diagnostic skills to the test.

Can you pinpoint the right diagnosis? Let’s find out!

Ready? Lets go!

Case #1:
A 45-year-old female presents with 2-3 days of nausea, vomiting, diffuse abdominal cramping, and three episodes of watery diarrhea. Her whole family has been sick with similar, but she has not gotten better. Her medical history includes a remote appendectomy and denies recent travel, medication use, or significant dietary changes. On exam, she is actively vomiting, looks dehydrated and her abdomen is mildly distended with diffuse tenderness.

Case #2:
A 28-year-old male presents with 2 days of nausea, vomiting, mild abdominal pain, and watery diarrhea. He reports fatigue, unintentional weight loss over the past week, and a headache. On exam, he appears dehydrated, is tachycardic and tachypneic with dry mucous membranes, mild abdominal tenderness

Case #3:
A 42-year-old male presents with 3 days of nausea, vomiting, and intermittent abdominal
discomfort, initially attributed to gastroenteritis. She reports occasional morning headaches and episodes of dizziness over the past month. On exam, she appears alert, with no focal findings but notes mild unsteadiness when walking.

Case #4:
A 1-year-old female presents with 2 days of fever, vomiting, decreased feeding, and intermittent abdominal discomfort. Her sister recently recovered from a upper respiratory tract infection but the patient does not have a cough or runny nose. Her parents note increased fussiness and lethargy and decreased urination. On exam, she looks well, is afebrile with mild abdominal tenderness but no other focal findings

Case #5:
A 30-year-old female presents with 3 days of nausea, vomiting, diarrhea, and abdominal
cramping. She reports unintentional weight loss and increased palpitations over the past month which she attributed to anxiety. On exam, she is tachycardic with warm, moist skin, slightly restless and otherwise unremarkable exam

Case #6:
A 28-year-old male presents with 3 days of nausea, vomiting, diarrhea, and abdominal pain, initially suspected to be gastroenteritis. He reports fatigue, muscle cramps and unintentional weight loss over the past month. On exam, he appears dehydrated, with low blood pressure and has diffuse, nonspecific abdominal tenderness

Answer:

These cases HAVE to be gastroenteritis, right? Vomiting, diarrhea, dehydration—it’s textbook!

In a busy ED, it’s easy to stop there. But missing subtle red flags can delay critical diagnoses. Let’s dig deeper and see what’s really going on in these cases!

Case 1:

Answer: Small Bowel Obstruction

Ok Doc, what points you to think of Bowel Obstruction?

While she did have symptoms of vomiting and diarrhea, her past surgical history puts her at higher risk since prior abdominal surgeries raise concern for adhesions leading to obstruction. She also did not settle down and persistent vomiting, distension, and lack of improvement despite “family exposure” set this apart from typical gastroenteritis

Case 2:

Answer: Diabetic Ketoacidosis (DKA)

Ok Doc, why did you suspect DKA?

The combination of vomiting, dehydration, weight loss, and tachypnea (Kussmaul breathing) points toward an acute metabolic issue rather than a simple GI infection

Case 3: Brain Tumor

Ok Doc, why did you suspect a brain tumour?

Chronic symptoms like morning headaches and dizziness, coupled with unsteadiness, suggest intracranial pathology rather than a GI illness .

Case 4: Urinary Tract Infection (UTI)

Ok Doc, why did you suspect a UTI?

Infants and toddlers often present with non-specific GI symptoms like vomiting when they have a UTI. No URI symptoms, changes in feeding, irritability, and fewer wet diapers raise suspicion beyond a typical stomach bug.

Case 5: Hyperthyroidism

Ok Doc, why did you suspect Hyperthyroidism?

Weight loss, palpitations, warm skin (excessive heat production) and tachycardia suggest a hypermetabolic state rather than a simple gastroenteritis.GI symptoms are often prominent but misleading in this endocrine disorder.

Case 6: Adrenal Insufficiency.

Ok Doc, why did you suspect Adrenal Insufficiency?

Chronic symptoms of fatigue and weight loss plus hypotension point to inadequate cortisol rather than an acute GI infection.

Wow Doc, there seem to be a lot of causes of vomiting and diarrhea, beyond just gastro!!

Yes!! There are various causes of vomiting in adults and children, these are only a few

The differential diagnosis for gastroenteritis includes a wide range of conditions that can mimic its classic symptoms.

These conditions can be categorized into

Medications/Toxins
Neurologic
Psychogenic
Endocrine/ Metabolic
Gastrointestinal

Adapted from Tome, June, et al. “A Practical 5-Step Approach to Nausea and Vomiting.” Mayo Clinic Proceedings, vol. 97, no. 1, 2022, pp. 1-10. Mayo Clinic Proceedings, doi:10.1016/j.mayocp.2021.11.002.

Take Home Points

While most acute GI complaints will turn out to be benign conditions, remaining alert to subtle clinical cues can make all the difference in identifying serious conditions early

Dig deeper when the clinical picture includes persistent symptoms, systemic clues, or red flags/ atypical features.

A thorough history and attention to subtle exam findings remain your best tools in uncovering the real diagnosis.

In uncertain cases, don’t hesitate to order targeted investigations to confirm or rule out alternative diagnoses.

References

American College of Emergency Physicians. “Clinical Policy: Critical Issues in the Evaluation and Management of Emergency Department Patients with Suspected Gastroenteritis.” ACEP, www.acep.org. Accessed 7 Jan. 2025.

Fauci, Anthony S., et al. Harrison’s Principles of Internal Medicine. 20th ed., McGraw-Hill Education, 2018.

Kliegman, Robert M., et al. Nelson Textbook of Pediatrics. 21st ed., Elsevier, 2020.

Ma, O. John, et al. Diagnostic and Statistical Manual of Emergency Medicine. McGraw-Hill Education, 2019.

Tome, June, et al. “A Practical 5-Step Approach to Nausea and Vomiting.” Mayo Clinic Proceedings, vol. 97, no. 1, 2022, pp. 1-10. Mayo Clinic Proceedings, doi:10.1016/j.mayocp.2021.11.002.

UpToDate. “Clinical Manifestations and Diagnosis of Gastroenteritis in Adults.” Edited by Robert M. Wachter, Wolters Kluwer, www.uptodate.com. Accessed 7 Jan. 2025.

UpToDate. “Evaluation of Nausea and Vomiting in Adults.” Edited by William L. Hasler, Wolters Kluwer, www.uptodate.com. Accessed 7 Jan. 2025.