Why do I have albumin in the urine?

Presence of albumin in urine may or may not be abnormal. It may be due to a variety of aetiologies. Even small amount of albumin in normal range may be detected on a routine test as '+', if the urine is concentrated. Even infections may show trace of proteins in urine. Usual next step is to go into detailed history for detecting potential causes, and check the ratio of creatinine to protein in urine, which gives a better indication of any significance of proteins present. Your physician may also get 24 hours urinary protein estimation if urinary creatinine protein ratio is found abnormal before proceeding to detailed investigations.