(A) These are general diagnostic blood studies (usually done on admission), but they are not reliable indicators of lithium therapy clearance. (B) These are the primary diagnostic tests to determine kidney functioning. Because lithium is excreted through the kidneys and because it can be very toxic, adequate renal function must be ascertained before therapy begins. (C) These are diagnostic blood tests used to determine the presence of endocrine (not renal) dysfunction. (D) These are other types of diagnostic procedures used to determine musculoskeletal, neural, and cardiac (rather than renal) functioning.