instruction: how many hours have passed since the last time patient 006-172277 received a laboratory test of the alt (sgpt) during this hospital visit?
response: SELECT 24 * (STRFTIME('%j', CURRENT_TIME()) - STRFTIME('%j', lab.labresulttime)) FROM lab WHERE lab.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '006-172277' AND patient.hospitaldischargetime IS NULL)) AND lab.labname = 'alt (sgpt)' ORDER BY lab.labresulttime DESC LIMIT 1