Overview
Globulin is usually calculated as total protein minus albumin and includes many immunoglobulins and other proteins.
Clinical Importance
Screen for hyper-/hypoglobulinemia
Prompt SPEP when globulin is unexpectedly high
Specimen Requirements
Calculated from total protein and albumin on the same specimen.
- Specimen: serum or lithium heparin plasma (method- and analyzer-dependent; follow the performing laboratory)
- Tube: gold/SST (serum separator) or green-top lithium heparin as validated locally
- Handling: invert gently; allow SST to clot fully before centrifugation; separate promptly
- Storage: refrigerate serum/plasma if testing is delayed per analyte stability limits
- Stability: analyte-specific; do not exceed institutional or manufacturer time/temperature limits
- Fasting: follow institutional/protocol fasting requirements when the ordered pathway requires fasting
Analytical Method
Arithmetic difference of measured total protein and albumin.
Instruments Used
Automated analyzers
- LIS/chemistry calculators using total protein and albumin results
Manual methods
- Manual subtraction
Reference Values
Typical adult SI examples below follow widely published international clinical chemistry practice (e.g., Tietz; Henry's). Always interpret against the method- and demographics-specific interval printed on the patient report (CLSI EP28-A3c). Neonatal, pediatric, pregnancy, and assay-generation intervals differ.
Typical published adult calculated globulin often about 20–35 g/L (2.0–3.5 g/dL); method-specific.
Interpretation
Common Causes of Increased Results
- High globulin; polyclonal or monoclonal gammopathy patterns warrant SPEP when indicated
Common Causes of Decreased Results
- Low globulin; antibody deficiency or protein loss contexts
Clinical Significance
- Protein panel interpretation
- Gatekeeper to electrophoresis
Factors Affecting Results
Pre-analytical
- Any total protein or albumin error
Analytical
- Propagated dye-binding biases
Post-analytical
- Ignoring A/G ratio unit consistency
Advantages and Limitations
Advantages
- No extra cost when TP and albumin are measured
Limitations
- Nonspecific . SPEP needed for characterization
Clinical Pearls
A quietly rising calculated globulin is often the first chemistry clue to order SPEP.
References
Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.
Textbooks
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 8th ed. Elsevier; 2022.
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
- Bishop ML, Fody EP, Schoeff LE. Clinical Chemistry: Principles, Techniques, and Correlations. 9th ed. Jones & Bartlett; 2022.
CLSI and Professional Guidelines
- International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Recommendations and reference measurement systems for clinical chemistry measurands (verify current IFCC documents for the analyte).
- Clinical and Laboratory Standards Institute. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Standard. CLSI document EP28-A3c. CLSI; 2010.
- Clinical and Laboratory Standards Institute. Collection of Diagnostic Venous Blood Specimens. CLSI standard GP41. CLSI.
- American Diabetes Association. Standards of Care in Diabetes. Diabetes Care (annual update).
- Kidney Disease: Improving Global Outcomes (KDIGO). Clinical Practice Guideline for Evaluation and Management of Chronic Kidney Disease.
- American Association for the Study of Liver Diseases (AASLD). Practice guidance related to evaluation of abnormal liver chemistries / liver disease laboratory evaluation (verify current AASLD publication and institutional adoption).
Frequently Asked Questions
Common questions about using this Globulin laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Globulin laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Globulin. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Globulin specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Globulin. Confirm collection details against your laboratory protocol.
Where are Globulin reference values listed?
See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.
How do I interpret Globulin results?
Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.
What analytical method is used for Globulin?
See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.
Are related laboratory tests linked from Globulin?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Globulin?
Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Clinical Chemistry topic.
What are the clinical pearls for Globulin?
See the Clinical Pearls section for concise laboratory practice notes associated with Globulin. Apply pearls alongside institutional protocols.
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