• There is no “test” (blood or other) that is solely diagnostic of Still’s disease; but labs can help make a diagnosis or manage disease
  • Laboratory tests are part of the evaluation and diagnostic process.
  • Lab, or blood, tests are primarily used to ensure the diagnosis, monitor the status of disease and affirm the safety of drugs in use.
  • Labs should not be used as screening tests for disease; instead, they are used to confirmation a specific diagnosis based on the patient’s symptoms and abnormal exam findings.
  • Some tests may be repeated over time to assess disease status (improved or worsened) or to ensure the safety of medications taken.
  • You should know which labs are affected by your condition or meds.  Lab test results should be given to you or retrieved so you can share with your doctors.
  • Keep a copy of your lab results in your personal medical chart.
  • Labs are reported as “normal” of “out of range” (meaning potentially abnormal).  It’s important to note that not all abnormal values will indicate a problem or disease.  Your doctor should contact you for lab abnormalities that require a change in medication or diagnosis.  Ask your doctor to explain (at your next visit) the results that are in the abnormal zone.
  • Labs in Still’s & Febrile disorders: If you have Still’s disease, many labs may be abnormal and indicate “Inflammation”.  It is the uncontrolled inflammation that leads to fever, rash, swollen joints, pleuritis, enlarged lymph nodes, etc.  Below is a table of the Lab Tests that are often “abnormal” during fever and active Still’s disease.
Lab Tests Commonly Done During the Evaluation & Diagnosis
Typically Abnormal Occasionally Abnormal Normal Values
WBC* Hgb/HCT Platelets* ESR* CRP* C3, C4* Liver Tests (AST, ALT) Albumin Aldolase* Ferritin* Glucose Creatinine ANA RF or CCP (ACPA) Uric acid Urinalysis
*Markedly elevated from inflammation
  • What do these tests mean?
    • CBC (or complete blood count) will include tests for anemia (hemoglobin [Hgb] or hematocrit [HCT}), white blood cells ([WBC] that may indicate inflammation or infection), and platelets (may be increased during inflammation; or very low with bleeding).
      • (WBC counts:  normal values are more than 3,000 and less than 10,000 cells/mm3. WBC counts greater than 15,000 can be seen Still’s disease, acute and chronic infections, other inflammatory and autoinflammatory disorders, and some cancers.
    • ESR (Erythrocyte Sedimentation Rate or “sed rate”) is a measure of inflammation, but may also be elevated with infection, pregnancy and other chronic conditions (like kidney or lung disease). Up to 90% of patients with Still’s disease will have an elevated ESR > 50 mm/hr. and over half will have very elevated levels (> 90mm/hr.) – all from inflammation.
      • ESR: normal is 0-20 mm/Hr.
      • ESR 20-50 would be a low-level elevation that is not diagnostic and seen in MANY conditions
      • ESR >50 is seen with inflammation, infection, pregnancy, anemia, kidney disease, chronic lung disease, autoinflammatory (FMF, TRAPS) and autoimmune diseases (lupus or rheumatoid arthritis)
      • ESR >100 is seen in fewer conditions including Still’s disease, other autoinflammatory diseases, infection, chronic infections, vasculitis, macrophage activation syndrome
      • For adults, a Sed Rate (ESR) that is much higher than your age (yrs.) is potentially worrisome and should be discussed with your medical provider.
    • High CRP (C-reactive protein):  CRP is a protein level that measures inflammation.
      • Up to 90% of patients with Still’s disease will have an elevated CRP > 1.0 mg/dl (or 10 mg/L).
      • CRP may also be elevated with infection, autoimmune disease (Lupus, RA) and other chronic conditions (like kidney or lung disease).
    • Ferritin is a measure of iron content in the body; and  may be very high in patients with inflammation.  Up to 50% of patients with Still’s disease will have an elevated ferritin level.
      • Ferritin levelsL normal is up to 150 ng/mL
      • Half of patients with Still’s disease will have an elevated ferritin (iron level), but alone, this is poorly predictive of Still’s disease
      • Extreme elevation of Ferritin (>2000) is more suggestive of Still’s disease. Yet extreme elevation of ferritin may also be seen in other disorders, including macrophage activation syndrome (MAS), HLH (hemophagocytic-lymphohistiocytosis), major liver injury/disease, severe COVID-19 and other severe infections, sepsis (blood poisoning), and iron overload disorders (multiple blood transfusions or hemochromatosis)
    • Liver tests includes the AST (SGOT), ALT (SGPT) enzymes coming from liver (or muscle); these may be elevated with inflammation or can be elevated with certain drugs or with hepatitis. The albumin is a protein that is included in a liver panel. The albumin may be low with severe inflammation or malnutrition.
    • Creatinine measures of kidney function
    • ANA (antinuclear antibodies): This is an antibody test usually found in Lupus (SLE) and other forms of autoimmune disease. This test is usually negative in Still’s disease patients.
    • RF (rheumatoid factor) or CCP (also called ACPA): This is an antibody test usually found in patients with rheumatoid arthritis (RA).   These tests are usually negative in Still’s disease patients.
    • Aldolase: This test is abnormal or elevated with inflammation, liver problems or muscle damage. Aldolase is commonly elevated with “active” inflammatory or systemic disease in patients with Still’s disease, autoinflammatory disease or other febrile disorders.
    • Uric acid: This is a test for gout and may be increased in patients with Gout or Psoriasis. This test is usually normal in Still’s patients.
    • C3 & C4 -These are complement levels. Complement C3 and C4 are proteins involved in your immune system defense and inflammation.  C3 and C4 levels are markedly elevated with inflammation.
  • Monitoring Labs: Laboratory testing or monitoring is usually part of drug safety monitoring with certain medicines used to treat Still’s and autoinflammatory disease patients. Below is a listing of tests needed, based on drug taken and how often they should be repeated.
What tests should you be getting?
Treatment Which Tests? How Often? Every:
Methotrexate CBC, AST, ALT, Creatinine 1-3 mos.
Azathioprine CBC, AST, ALT 2-3 mos. 
Plaquenil Eye Exam Yearly
NSAID CBC, Creatinine, AST, ALT 3-6 mos.
TNF inhibitors (Enbrel,Humira) CBC, AST, ESR, CRP  6 mos.
Stills disease CBC, AST, ESR, CRP 6 mos.
NSAID: Advil, Aleve, Celebrex, Mobic, Voltaren, Relafen, Naproxen
  • Imaging Tests for Diagnosis: your doctor may do imaging tests to establish the diagnosis and identify inflammation involving the organs (lungs, heart, liver, spleen) or lymph nodes. Common imaging tests include:
    • Chest X-ray (CXR): these are helpful if you are short of breath, have persistent chest pain (possibly from pleurisy) or are losing weight.  CXR may identify fluid on the outside of the lung (pleuritis) that causes focal chest pain with breathing (pleurisy), or on the outside layer of the heart (pericarditis).  CXR may identify enlargement of lymph nodes in the chest or enlargement of the heart.
    • MRI (magnetic resonance imaging): MRI of the chest or abdomen can be done to visualize the lungs, heart, liver, spleen, kidneys and lymph nodes and may be able to detect organ or lymph node enlargement or inflammation.
    • CT (computerized tomography) scans of the chest, abdomen or pelvis can be done to visualize the lungs, heart, liver, spleen, kidneys and lymph nodes and may be able to detect organ or lymph node enlargement or inflammation. 
    • CT or MRI scans are sometimes done to look for causes of unexplained fever.
    • Ultrasound (US) of the abdomen is often done to assess the size and status of the liver, spleen, or kidneys.  
    • (Kidneys are not usually affected by Still’s disease; and are only rarely affected by secondary amyloidosis with long-standing Still’s disease)
John Swope
Author: John Swope

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