Hello, Concentrated urine often smells strong. The smell of onion suggests sulfurous smell and urinalysis should be done to exclude infection, salts and pigments. Please increase the intake of liquids maintain proper genital hygiene. You should also test for albuminuria and get your blood pressure checked regularly. Take adequate rest preferably in left lateral position. Get periodic sonograms. Avoid excess salt. Urinary alkalinizers may be taken if necessary after consulting your specialist. Hope this helps.