I have MGUS. Try not to worry. You are correct that VERY few end up with any problems. Further check of blood & 24 hour urine will be necessary. A bone survey (x-rays of all bones) or a full body bone scan is also recommended.

I'd hold off on the very invasive bone marrow, unless other tests indicate possible myeloma or lymphoma.

You should consider MrsD's suggestions and your doctor will also follow up with testing every 6-12 months.