Welcome to HCM, What a blow when you have been working so hard to find out you might have an HDL of 18. What I would say to you if you were my patient is to have a repeat fasting lipid profile. Then, you may contact us and we can review your labs and strategies to adjust any risk problems such as high triglycerides,LDLs, HDLs - the whole profile to look at. Now, I searched the internet and found all sorts of information on allopurinal being used for gout . So, I went to google Search. I could find nothing about allopurinal affecting cholesterol. I looked it up in the Food,Medication Interactions handbook and there was no reference to allopurinal affecting lipids. Regardless, the 2017 American Association of Clinical Endocrinologists and American College of Endocrinology Guidelines for Management of Dyslipidemia and Prevention of Atherosclerosis do not mention Allopurinal at all in the lowering of HDL. They comment that one should exercise using cardiovascular routines, lose weight if overweight and get enough sleep to raise that HDL. It seem like you are doing many of those things. I welcome you to come back and work with one of our clinicians if your lipids are high or low in the wrong areas and we can work up a plan. Just out of curiosity, you should take your allopurinal with a low purine diet. Are you doing that? Oh, and there is a major warning about alcohol use which would be in your low purine diet . We can help you there as well if you see a dietitian or you may seek on out on your own. Let me know if you need anything else, Regards, Kathy Shattler