Dear Dr. Roach: I am a white male, 70 years old, over six feet tall and weigh 140 pounds. I am healthy except for lymphocytic colitis, which is under control with Imodium.
My physical last year included a complete blood count and an automated differential. Everything was good except the RDW. It was 18.7 per cent, with a standard range of 11.5 to 14.2 per cent. The MCV was 96, and I had no anemia. My primary physician said to not worry about it.
I recently had a pre-op visit for some surgery, and the RDW was 21.1 per cent. I asked the
surgeon if this was a concern, and he said he did not know and that I should contact my primary again for further analysis. Per the internet (Mayo Clinic, for example), this can be an indication of chronic liver disease or anemia. Should I contact my primary doctor, a specialist or just not worry about it?
L.M.
The RDW is the 鈥渞ed cell distribution width.鈥� It鈥檚 a measurement of how similar the cells are in size to each other. A large RDW indicates that there are an unusually large number of cells that are bigger and smaller than the average (which is the MCV, 鈥渕ean corpuscular volume鈥� 鈥� that鈥檚 just the red cell again). In people who have vitamin B-12 deficiency, for example, the red cells are abnormally large; in people with low iron, the cells are abnormally small. Someone with both iron deficiency and B-12 deficiency might have a normal MCV but a large RDW.
My experience is that the RDW by itself is not particularly helpful, which is why I suspect your primary doctor isn鈥檛 worried about it. With a history of colitis, I would want to be sure you don鈥檛 have iron deficiency (iron deficiency can happen before any anemia shows up).
It鈥檚 scary to read about the many causes of a finding in your labs, but it鈥檚 wise to not get too worried about conditions that you are unlikely to have. It鈥檚 not necessary for a physician to chase down every possibility, but they must stay alert for early signs of conditions. Finding that balance is one of the hardest jobs for a clinician.
Dear Dr. Roach: Over a decade ago, I had a heart attack for which I had a stent put in. I was prescribed Lipitor. I had a bad reaction to Lipitor and was subsequently given Vytorin, which works well. Now I am being changed to rosuvastatin. Will this new drug work as well as the Vytorin? Most important, though, will I have the same side effects as I did with Lipitor 鈥� memory problems and soreness?
B.L.
People with blockages in the arteries of the heart, with or without a history of heart attack, surgery or stent, benefit from statin drugs, which reduce the risk of recurrent heart attack and death. Atorvastatin (Lipitor) and rosuvastatin (Crestor) are two of the most potent statin drugs. Vytorin is a combination of simvastatin (Zocor) and a non-statin drug, ezetimibe.
All statin drugs can have side-effects. Muscle aches or soreness and memory issues are reported side-effects; however, sometimes people get these side-effects from one statin but not another. There is no predicting whether the rosuvastatin will cause any problems for you.
I don鈥檛 understand why you are switching from a treatment that is working well; I suspect it鈥檚 an insurance problem.
If so, you may be able to get back on Vytorin if the rosuvastatin doesn鈥檛 work. I have had to write similar letters to get medications approved for my own patients.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected].
