Screening Blood Panel to Evaluate New Chronic Pain Patients
Name a disease or a medical condition and you can almost always identify a screening blood panel that physicians obtain when they initially evaluate and start treatment on a new patient. This article professes the belief that chronic pain is no different. The “Decade of Pain” plus a lot of earlier clinical experience and research has given us enough information to recommend a standard blood panel to initially evaluate and begin treatment in a new, chronic pain patient.
I recommend a standard screening blood panel which, I have found, helps determine severity of pain and disability and helps distinguish the addict from a legitimate pain patient. While there may be different and even superior recommendations from other physicians, the blood panel recommended here is simple, relatively inexpensive, and available through all U.S. laboratories.
The panel recommended here is intended only for chronic pain and not for any other disease state (see Table 1). Most important, it is generally independent of any underlying cause of chronic pain. The physician may wish to add other blood tests to the panel. For example, one might want a glycosolated hemoglobin (HbA1c) in a diabetic neuropathy case or an antinuclear antibody (ANA) in a fibromyalgia-systemic lupus case. The panel recommended here is based on the knowledge that severe chronic pain produces inflammation and stimulatory or suppressive affects on the pituitary-adrenal-gonadal axis.1-4
Why Was This Panel Selected?
Four of the blood tests in the panel are based on chronic pain’s major affects on the adrenal gland and the inflammatory response.4-6 Testosterone is the hormone in males and females that often is lowered with even low dosages of a weak opioid.7 Severe chronic pain, per se, may also have an adverse affect on testosterone blood levels.
Although pain’s affect on the pituitary-adrenal-gonadal axis is well known, it is somewhat uncertain as to how pain causes an inflammatory response and an elevation of the erythrocyte sedimentation rate (ESR) and C-Reactive protein (CRP).1-4 Although some underlying cause of pain such as rheumatoid arthritis or hepatitis may cause a serum elevation of the ESR and CRP, it appears that a pain site unrelated to any underlying disease may cause the ESR and CRP to elevate. It is now documented that the ESR will be elevated in uncontrolled pain and will normalize when pain control is achieved.5
Elsewhere is this issue of Practical Pain Management, Dr. Steven Singer reveals that cytokines, a very sensitive indicator of inflammation, may be elevated when the ESR and CRP are normal. The main importance of an elevated ESR, CRP, or cytokine is that it documents that an inflammatory site is present. It is theorized here that a peripheral pain site consists of a damaged nerve as well as damaged blood vessels and lymph drainage (see Figure 1) The site collects cytokines, heme products, leucocytes, and excess electricity which produces heat and inflammation. Fundamentally, the pain site is a non-dermal wound that may be of microscopic size.
This article was stimulated by three patients referred to me last week. In each case, I was initially unsure of the severity of their pain. All three patients claimed to have some days in bed or reduced work time, but they were amiable, pleasant, and appeared mentally stable. Only after their blood screening panel, did I fully consider any of the three to be a severe, chronic pain patient.
Case No. 1
A 62-year-old female is the manager of a local credit union underwent a hip replacement about a year ago. Since then her hip and leg functioned quite well but she claimed her pain was so severe she could only work a half day. Standard dosages of hydrocodone/acetaminophen were not sufficient to control her pain. Her screening panel revealed a high ESR (65mm/hr; normal is less than 30) and CRP (3.20mg/dl; normal is less than 0.80). Her morning cortisol was borderline high (20.3mcg/dl; normal is 4.0-20.0mcg/dl).
Case No. 2
A 48-year-old male professional had been diagnosed with anklylosing spondylitis. He was referred because his daily oxycodone dosage had begun to approach about 300mg. Although he described his pain as “tolerable” with medication, he complained of weakness and fatigue. His screening lab results amazingly showed a morning cortisol of only 0.9mcg (normal is above 4.3), and pregnenolone of less that 10ng/dl (normal is 20 to 150ng/dl). His testosterone was 66ng/dl (normal is 240-825).
Case No. 3
A 69-year-old retired female complained of painful knees and back. One knee had been replaced. Causes of her problems apparently were multiple vehicle accidents throughout her life. Her pain medication was tramadol which provided almost no relief. Screening blood panel showed a high morning cortisol of 26.6mcg/dl, (normal is below 22), ESR of 53mm/Hr (normal is below 30), and CRP of 1.1mg/dl (normal is below 1.0).
Interpretation of Screening Results
Uncontrolled pain causes a stress-type release of pituitary adrenocorticotrophin hormone (ACTH) which over-stimulates the adrenal gland to raise serum levels of cortisol and other adrenal hormones including catecholamines.1-4 It is this reason that pulse rates and blood pressure may rise in a pain flare or with chronic, uncontrolled pain. Two of the three cases described here had high or borderline high cortisol. This clearly suggests uncontrolled pain.
One patient had very low cortisol and pregnenolone which is the precursor of all adrenal hormones. If serum pregnenolone is low, it is assumed that production of all adrenal-produced glucocorticoids and androgenic and estrogenic compounds are reduced since pregnenolone is the precursor of all these compounds. Cortisol levels less than one indicate severe adrenal exhaustion which can result over time from excess adrenal stimulation.3 Levels less than 1.0mcg/dl are often not compatible with life, so this patient is extremely ill and requires vigorous pain control. The low adrenal and testosterone levels certainly provide an explanation for fatigue and weakness.
An admission-to-treatment testosterone level serves two purposes. A low level indicates severe, debilitating illness or opioid suppression of follicle stimulating hormone (FSH) in the pituitary.7 If the testosterone level is normal it provides a baseline to judge a lowered testosterone should opioid treatment produce this complication later in treatment.