instruction: what is the maximum total cost of the hospital, which includes the laboratory urinary sodium test?
response: SELECT MAX(t1.c1) FROM (SELECT SUM(cost.cost) AS c1 FROM cost WHERE cost.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.patientunitstayid IN (SELECT lab.patientunitstayid FROM lab WHERE lab.labname = 'urinary sodium')) GROUP BY cost.patienthealthsystemstayid) AS t1