It is important to recognize that laboratory values – as well as other common values, scales and grades in general (such as ROM values) utilized by PTs are simply guidelines and not absolute markers. Values often differ depending on the respective authority cited (e.g. APTA, American Medical Association AMA etc.). Furthermore, what may be considered normal in one individual may be considered abnormal in another and vice-versa. It is for this reason that lab values are usually given as a range and not as a single figure. Finally, it is unlikely that you will be tested on your knowledge of the absolute lab values of any particular authority (especially extreme values of any particular range) but rather your knowledge of the broad ranges applicable to the major tests.
Goodman CC provides a very useful guideline for normal platelet values. [1] Italics in the tables are mine.
Adult and child (>1yr) 150,000 – 350,000/µL (microliters)
Critical low <20,000/µL (Thrombocytopenia. Some sources list <30,000/µL as the critical low value)
Critical high >1,000,000/µL (Thrombocythemia)
She references Gold and Hennis for her table (used with permission) on exercise guidelines for different platelet values/levels. [2]
PLATELET COUNT EXERCISE GUIDELINES
<10,000 Usually transfused
<20,000 ADLs, AAROM – AROM but no antigravity or resistive exercise; guard carefully
20,000 – 30,000 Light exercises (No PROM; light AROM permitted; walking as tolerated)
30,000 – 50,000 AROM, submaximal isometrics, stationary bicycle, walking as tolerated, aquatic therapy. NO prolonged stretching or resistive exercise
50,000 – 150,000 Minimal to moderate resistive exercises allowed; sexual intercourse; MMT without restrictions; swimming; low bench stepping; bicycling (no grade; flat only)
>150,000 Normal activity (unrestricted)
Goodman posits that withholding therapy because platelet values fall into the ‘no exercise’ range is not well founded in the literature; it is a guideline not a standard. The table also covers exercise guidelines for different hemoglobin (Hgb) levels, hematocrit (Hct) levels and White Blood Cell counts. I highly recommend it. [3]
Perhaps Goodman says it best when she concludes, ‘ Please keep in mind, the values listed are considered ‘normative ranges’ but each lab will use its own values for the reference (normal) range. In addition, each facility(and even individual physicians) may have individual guidelines that supersede these values. All patient parameters must be taken into consideration as we ‘treat the person, not the number’. The values provided here are guidelines and do not substitute for clinical judgment’.
Reference 1: Irion GL, Goodman CC: Laboratory tests and values. In Goodman CC, Fuller KS; Pathology: Implications for the physical therapist. 3rd Edition. St. Louis, 2009, Saunders [an imprint of Elsevier]. Pg 1637 – 1668., Reference 2: Gold E, Hennis S: Therapeutic implications of laboratory values, 2009. Unpublished data; PowerPoint presentation., Reference 3: Goodman CC, Snyder TEK. Differential Diagnosis for Physical Therapists. Screening for Referral. 5th Edition. Elseviers Saunders, 2013. Lab values listed in tables on the inside of both the front and back covers.
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