I'm a CMA and have been for 7 years. Here is the rundown on the CMA/LPN/CNA.
As a CMA, I work in a clinic setting. CMA's are specifically trained for work in doctor's offices, not hospitals. Though, some hospitals are now hiring CMA's and retitling them Patient Care Assistants. In the clinic, I do phlebotomy, give injections and oral meds, catherize, do telephone triage and assit with minor surgeries. I also do OB teaching/counseling and a variety of other duties. I LOVE IT! The LPN's in my clinic do the exact same jobs as I do with the same exact pay. However, as a CMA I do not deal with IV's, work with speciality physicians like Cardiology, urology, etc, handle walk-in testing like pregnancy tests or do any independant patient assessments.
In the hospital, LPN's do many,many different things. PRetty much total patient care, with the exception of IV's ( depends on the state).
CNA's do not assist a physician in the same way a CMA/LPN does. They take care of a patient's physical needs like bathing, grooming, exercising, vitals, etc. They do not draw blood, give meds ( here in WI anyway) or assist with procedures.
I have absolutely LOVED my experience as a CMA, and though I am now a nursing student, I haven't regretted being a CMA at all. It's very exciting, especially if you work in a clinic that will allow you to use all of your skills. Most clinics are hiring CMA's and the demand for them is great.
I currently make $13 an hour as a CMA, but that's after 7 years. The pay isn't as much as a hospital LPN would make. The CNA's at our hospital make about the same as I do.
My advice is that CMA training is always valuable. However, if you're long term goal is to be an LPN/RN, go for it right away. You will make more money and have many job opportunities. For me, being a CMA was beneficial because I have little kids and dont have to work nights/holidays, etc. I will be taking a distance CMA-LPN-RN program shortly, as I am ready for more knowledge and responsibility.
If you have more questions about CMA, feel free to pm me. Good luck in what you decide!