Creatinine levels relate to both muscle mass and to kidney function. As you age, your muscle mass decreases but your kidneys tend to function less effectively. The net result is not much change in creatinine levels in the blood as you get older.
As a result, California employers are required by law to have workers' compensation insurance, even if they have only one employee. And, if your employees get hurt or sick because of work, you are required to pay for workers' compensation benefits.
Under the state and federal Family and Medical Leave Acts (FMLAs) an employer can count an employee's time out on workers' compensation as family and medical leave as long as the employee is out for a reason that meets the FMLA requirements.