I worked in rural health in Kentucky for twenty years, then in urgent treatment centers in Denver. All sorts of patients pop up in primary care and in UTCs. Most have easily identified complaints: UTI, sinusitis, flu. Others are there for regular refills, for hypertension or cholesterol meds. There were a few patients I remember whose presentations were less straightforward, whose diagnoses were more elusive.

The following two patients presented with signs and symptoms of one disease and actually had an entirely different one. I call these cases the “Look-alikes.”

A 45-year-old Hispanic gentleman presented with yellow nodules on his arms and hands. His English was marginal. A staff person provided translation for me. These nodules had appeared in the preceding month or two. I immediately thought of hyperlipidemia. I had had a patient years before with massive elevations of triglycerides (over 1,700) and with secondary pancreatitis. He too had eruptions of skin nodules. His were collections of lipids excreted into the skin.

I drew labs for a lipid panel. I started him on Lipitor for presumptive hyperlipidemia. He was paying out of pocket and did not want to wait for the lab results to come back before starting treatment.

He returned two weeks later. The nodules had gotten worse, not better. His lipid panel was normal. I was at a diagnostic dead end. The physician with whom I worked was in his eighties. I asked his advice. He said: “Gout. They look like tophi related to gout. Test for uric acid levels in the blood. Give him Allopurinol.”

Dr. 80-year-old was right. The patient tested positive for high serum levels of uric acid, and the deposits melted away with treatment for gout.

Who knew? I thought my presumptive diagnosis of hyperlipidemia was brilliant. Apparently not.

A second patient was a Caucasian woman in her early fifties. She was lying on the exam table, in some distress. She had been vomiting. She felt woozy. Her past medical history revealed a gastric bypass surgery some years ago. She denied any history of diabetes.

We quickly collected urine for urinalysis. It revealed sky-high ketonuria. I was used to seeing patients present in diabetic ketoacidosis, with ketones and glucose both spilling into the urine. Her urine glucose was normal, however. We did a fingerstick blood glucose. I was hoping to see hyperglycemia, which I knew how to treat. To my dismay, she had normal glucose levels. While we were pondering the mystery of her ketoacidosis, we started intravenous fluids.

I left the exam room and did a quick read in my medical bible, Current Medical Diagnosis and Treatment. This was before Google became the go-to diagnostician. My source explained that ketoacidosis can occur with alcoholism, especially in someone with malnourishment, which is always a risk after gastric bypass.

I returned to the exam room and questioned her further. Did she drink alcohol? She told me that the surgeon who did her bypass had advised her to avoid alcohol. She nonetheless drank one or two glasses of whiskey daily.

I brought her in briefly to the hospital to get her metabolites straightened out and advised her to stop drinking alcohol, as her surgeon had advised.

For some reason, I remember these cases with fondness, for the pleasure with which a murky diagnosis resolved itself and for the “Aha!” moment it provided.

Janet Tamaren is a family physician and author of Yankee Doctor in the Bible Belt: A Memoir.