Have you ever had your Thyroid Levels checked? Hypothyroidism(which means low thyroid)can cause hair loss. Do you feel fatigued, constipated, overly cold a lot of the time, depressed, fuzzy headed, dry skin? These are all symptoms of low thyroid. I'm not sure about the bright yellow urine, but I have Hypothroidism, and do seem to have dark urine a lot and have had several Urinary Tract Infections. Do you have lower back pain, pain in the lower pelvic region- which may get worse upon urination but is somewhat releived afterwards, itching or burning upon urination, blood in urine, sick to your stomach or dizziness, fever, achiness? These are all symptoms of UTI. You don't have to have ALL symptoms present for either condition. I hope this helps....