Why Would My Cat's Creatinine Jump Dramatically -- Male Cat

Why would my cat's creatinine jump dramatically -- male cat in first stages mild CRF with a Canadian value of 225 at the end of October 2014. Now, it is 1178. Cat was fine -- lively, good appetite -- showing no symptoms of CRF except excessive water intake. Suddenly, 6 days ago he vomits and stops eating. I get the bloodwork done and it shows that the creatinine made this jump -- phosphorus and potassium also as well as BUN/UREA. Still no protein in urine.
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