Unravel complications of outpatient coding for chronic kidney disease
The kidneys filter wastes and excrete fluid when the blood is forced through the internal structures of the kidney. However, various diseases can affect how well the kidneys function and cause various kidney diseases.
Chronic kidney disease (CKD) is the permanent alteration in the kidney’s ability to perform filtration and reabsorption functions. Patients with CKD can come into an outpatient clinic or may be admitted as an inpatient, either for the CKD or some other condition.
Outpatient coders need to be able to recognize the stages of CKD and understand what tests and procedures providers may perform in a clinic or other outpatient setting.
The patient’s medical record is not only a document for billing, but also a chronological record of the patient’s care, says Debra Lawson, CPC, PCS, a consultant with Nephrology Billing & Management Services, LLC, of Rogersville, Tenn. In an audit, the medical record provides the only protection for the patient and the provider.
“You don’t see an auditor come in, put an arm around the physician, and ask, ‘what were you thinking when you treated this patient?’” Lawson says.
If the provider doesn’t document well, the coder can’t assign the correct codes and can’t defend the coding during an audit, she adds.
ICD-9-CM CKD coding
Glomerular filtration rate (GFR) measures the creatinine level of the kidneys and how well the kidneys function. Physicians generally look at GFR during a patient’s annual physical, Lawson says.
Muscles generate creatinine as a waste product. Because people have different amounts of muscle, they produce different amounts of creatinine. The GFR allows physicians to compare kidney function across the population because it accounts for age, race, and gender, factors that impact how much muscle someone has, Lawson says. As kidneys lose function or filtering ability, they do not filter waste correctly and the creatinine level in the blood start to rise.
A patient with CKD progresses through as many as six stages, according to the National Kidney Foundation. Stage I CKD is a GFR greater than or equal to 90. “If you look at the statistics, it is safe to say everyone has Stage I CKD, but a diagnosis is based on additional factors,” Lawson says.
Stage II CKD is a GFR of 60–90. This is mild kidney disease, says Lawson. At this stage, most people don’t even realize they have a problem.
A GFR of 30–59 is Stage III moderate kidney disease. These patients may still be symptom free, Lawson says.
Stage IV CKD is a GFR of 15–29. This is severe kidney damage and at this point, the physician starts preparing the patient for kidney replacement therapy, Lawson says.
A GFR of less than 15 is Stage V CKD and is also kidney failure. If patients have a GFR less than 15 and are on dialysis, they are considered Stage VI and are diagnosed with end-stage renal disease (ESRD), Lawson says. The difference between Stages V and VI is dialysis, she adds.
Coders will find the ICD-9-CM codes for CKD in the 585 series, says Jennifer E. Avery, CCS, CPC-H, CPC, CPC-I, senior regulatory specialist with HCPro, Inc., in Danvers, Mass. Coders need to chose the appropriate fourth digit to identify the stage of CKD, she adds.
ICD-9-CM codes for CKD are:
- 585.1, Chronic kidney disease, Stage I
- 585.2, Chronic kidney disease, Stage II
- 585.3, Chronic kidney disease, Stage III
- 585.4, Chronic kidney disease, Stage IV
- 585.5, Chronic kidney disease, Stage V
- 585.6, End stage renal disease
- Chronic kidney disease, Stage V requiring chronic dialysis
If the physician does not document the stage of CKD, report code 585.9 (unspecified), Avery says. If the provider documents both a stage of kidney disease and ESRD (585.6) in the record, code only 585.6, she adds.
Signs and symptoms of CKD
In the early stages of CKD, patients often do not feel sick, Lawson says. But as the disease progresses, patients may :
- Need to urinate more or less often
- Feel itchy or numb
- Lose their appetite or experience nausea and vomiting
- Notice swelling in their hands or feet
- Have trouble concentrating
- Notice their skin darken
- Experience muscle cramps
The kidneys not only filter fluids, they also filter toxins. As a result, when the kidneys start to fail a patient may experience changes in mental status, Lawson says.
Patients with CKD may also suffer from a sudden loss of the ability of the kidneys to remove waste and concentrate urine and/or excrete electrolytes. The abrupt loss of kidney function is acute kidney failure (AKF) or acute kidney injury, Lawson says.
AKF and CKD are two separate and distinct conditions, Avery says. AKF has an abrupt onset and is potentially reversible. CKD progresses slowly over time and can lead to permanent kidney failure. If both acute and chronic kidney failure are clearly documented, code both conditions, she says.
Code the AKF primary with ICD-9-CM code 584.9, followed by the stage of CKD prior to the exacerbation, Lawson adds.
Testing for CKD
The National Kidney Foundation recommends three tests for CKD:
- Blood pressure measurement
- Spot check for protein or albumin in the urine
- Calculation of GFR based on a serum creatinine measurement
High blood pressure can lead to CKD or it can be a symptom that the kidneys are already failing, Lawson says. A primary care physician unable to get the patient’s blood pressure under control may send the patient to a nephrologist, who can check to see if the high blood pressure is underlying CKD.
Depending on which specific test the physician orders, coders may report one or more of the following CPT® codes:
- 82043, urine microalbumin, quantitative
- 82570, urine creatinine
- 82565, serum creatinine
- 84520, blood urea nitrogen (BUN)
Healthy kidneys take waste out of the blood but leave protein. Impaired kidneys may fail to separate a blood protein called albumin from the wastes. At the start of kidney disease, only small amounts of albumin may leak into the urine. This condition, known as microalbuminuria, is a sign of deteriorating kidney function, Lawson says.
The amount of albumin and other proteins in the urine increases as the kidneys deteriorate. This condition is called proteinuria and coders would report it with ICD?9-CM code 791.0.
Blood carries protein to cells in the body. After the cells use the protein, the remaining waste is returned to the blood as urea, a compound that contains nitrogen. Healthy kidneys take urea out of the blood. If the kidneys are not working urea stays in the blood.
A BUN measures the amount of urea in the blood that contains nitrogen, Lawson says. If a person's BUN is more than 20 mg/dL, the kidneys may not be working at full strength. Heart disease and dehydration may also cause an elevated BUN.
In addition, a physician may order an ultrasound, computerized tomography (CT) scan, and magnetic resonance imaging (MRI) to find unusual growths or blockages to the flow of urine, Lawson says.
A physician may also perform a kidney biopsy, especially if a kidney transplant starts to fail. Report a kidney biopsy with CPT code 50200. Remember that the physician usually takes three core samples for the biopsy, but coders should report only one unit of 50200, Lawson says.
E-mail your questions to Senior Managing Editor Michelle A. Leppert, CPC-A, at firstname.lastname@example.org.