The nurse is caring for an adult client who is taking digoxin. Which laboratory value should be reported to the healthcare provider immediately? Reference Range: Sodium [Adult 136 to 145 mEq/L (136 to 145 mmol/L)] Digoxin level [0.8 to 2.0 ng/mL (0.6 to 13 nmol/L)] Potassium (K+) [Adult: 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)] Creatinine [0.5 to 1.1 mg/dL (44 to 97 μmol/L)]