Thursday, February 3, 2011

Continuing Medical Education Panel sponsored by the American Orthopedics Association for Surgeons: Total hip Atheroplasty: Is there a MOM bearings controversy? (Part Five of Five)

Jerry Leiken MD:  Professor of Medicine and Pharmacology at Rush Medical Center and University of Chicago (Medical Toxicologist)

My notes (5 of 5)
Systemic Issues surrounding the Cr and Co metal toxicity
Cobalt
1.   Cases of chronic metal toxicity are rare in North America.
2.   Cobalt has been around for centuries
3.   It is a naturally occurring element and is found in many foods such as fish, cocoa, green leafy vegetables.  It is a nutritional component of B12.
4.   It is found in drinking water and the average intake for humans is 5-45 micrograms per day.
5.   Classic systemic “toxidrome” cases of Co toxicity
a.      Cardiomyopathy ( might occur at 6 milligrams per day)
b.      Goiter (thyroid hyperplasia)
c.       Metablolic acidosis (lactic acidosis)
d.      Polycythemia (not seen after inhalation)
6.   Normal Cobalt levels range from
a.      Bood: .6-1.8 mcg/L
b.      Urine: .1-2.2
c.       Hair: .05 mg/kg
d.      Nails: .06 mg/kg
7.   Chelation is never used for Chronic neurotoxicty
a.      If the Cobalt is in the blood, Chelation does make the metal more soluble and amenable to excretion in the urine within 3 months of exposure.
b.      Chelation is not effective once the metal is in the hard or soft tissue.
c.        Chelation is of questionable use for Co toxicity. “ Its actual efficacy and indications remain unclear.”  From poisiondex.
Chromium
1.      Considered to be relatively non toxic except for the hexavalent form which is considered to be a carcinogen.  This metal contains the trivalent form of Cr.
2.      Toxic dose has not been established
3.      Possible toxic effects:
a.      Acute tubal necrosis
b.      Seizures
c.       Acute hepatitis
d.      Coma
4.      Normal levels
a.      Blood: .7-20 mcg/l
b.      Urine  .24-.18 mcg/l
5.      A physical exam is not helpful to detect issues surrounding this metal toxicity.
The Father of Toxicology in the 1400s:
“Everything is a poison.  There is nothing which is not. Only the dose differentiates a poison from a remedy.”
[connie’s observation to this lecture:
·         While there are few cases of toxicity published in the medical literature from these implants, I wonder about the following:
o   These MOM implants haven’t been around all that long such that the effects of them systemically have been studied.
o   I think 4 of the 6 cases identified were conducted upon autopsy.  How many hospitals run organ toxicity exams for Cr and Co after death of an implant patient?
o   Measuring toxicity is dicey at best with the testing we have available.

·         I have more questions after having listened to the toxicity lectures than I did prior to the lectures albeit, I did find them informative in terms of reporting what we know.  What we know is not my concern.  I am concerned about what we don’t know given what we know now appears to be minimal on this topic.]
Connie

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