Simplify chronic kidney disease coding through clinical insight

So often, we talk about the challenge of getting physicians to document the details. But what about when despite the presence of proper documentation, coders still struggle with various clinical definitions? Case in point—chronic renal failure vs. chronic kidney disease (CKD).

From a coding perspective, the two are interchangeable. But the terms “acute” and “chronic” correspond to very distinct disorders. When it comes to this condition, coders often find the following aspects challenging:

  • Staging
  • Coding
  • Sequencing

“As opposed to acute renal failure, chronic kidney disease is one of slow, steady progression. You can develop chronic kidney disease to some degree after an episode of acute renal failure, but fortunately most acute renal failure resolves and you have minimal changes to the kidney,” said Garry L. Huff, MD, CCS, director of Garry L. Huff, MD, Inc., and CEO at Advanced Technical Medical Data Systems in Eads, TN, who spoke during HCPro’s November 9, 2010, audio conference, “Acute and Chronic Renal Failure Documentation: Understand the Clinical Indicators for Querying and Coding Accuracy.”

CKD is a manifestation of many different chronic disease processes with the predominant ones being diabetes, hypertension, and immune complex diseases, such as lupus and idiopathic forms of glomerulonephritis, Huff said. Also, CKD often results in long-term systemic complications (e.g., hyperparathyroidism, bone diseases, and anemias of CKD).

Principal diagnosis selection for patients with CKD is particularly challenging because their histories often consist of intermittent hospitalizations, with different problems at different times.

“This is much like coronary artery disease, which can present atrial fibrillation one time, and the next time heart failure, and the next time with a myocardial infarction,” Huff said. “So [CKD] can present many different faces, and therefore many different principal diagnoses.”

Understand the definition of CKD

The most important criterion of CKD is that the patient has had renal abnormality (structural or functional) for more than three months to be considered chronic, Huff said.

Indicators of kidney damage can include either structural damage or gross pathological damage, such as polycystic kidney disease and small hypoechogenic contracted kidneys on imaging studies (e.g., ultrasound), or functional markers of damage, such as abnormal blood and urine tests (e.g., elevated serum creatinine or proteinuria).

In addition, physician documentation should define the degree of functional impairment (i.e., stage) in terms of impairment of glomerular filtration rate (GFR), which is the amount of blood that the kidney can filter within a minute.

Recognize the five stages of CKD

There are clinical tips that can help coders distinguish between the five stages of CKD, as defined by the National Kidney Foundation.

The foundation developed equations derived from the serum creatinine in the blood that physicians can use to accurately predict GFR levels without conducting numerous urine collections or other special tests. One of the more helpful calculations is the Cockroft-Gault Equation, which is:

(140 - age of patient) x the patient’s weight (in kilograms)
Serum creatinine value x 72

For females, multiply by 0.85 to appropriately adjust this number

“The stages of CKD obviously have important ramifications in terms of the need for specific treatments at specific stages,” Huff said.

People are expected to have certain symptoms at certain stages, said William E. Haik, MD, FCCP, director at DRG Review, Inc., in Fort Walton Beach, FL. “You obviously wouldn't expect somebody with Stage I CKD to have acidosis related to the renal injury,” Haik said. “So you would query on the basis of the GFR, not the accompanying symptoms. These are just guidelines to provide you a clinical assessment of where they might be.”

The stages are as follows:

Stage 0. This indicates a person who has a disease process but he or she has no evidence of kidney damage by urinary markers, serum creatinine, or x-rays. However, the person is nonetheless at risk for developing CKD. For example, a person with diabetes could be Stage 0, so his or her physicians would need to check urinary proteins each visit to monitor the development of damage biomarkers.

Stage I (code 585.1). If a physician subsequently found proteinuria, but the patient had a normal creatinine GFR greater than 90, this case is considered Stage I CKD.

“At this stage, you want to make sure that the patient has adequate nutrition.” Huff said. “Also if they’re diabetic, we will probably institute [angiotensin-converting enzyme (ACE)] inhibitors in that patient to retard the development of the progression of the diabetic renal disease.”

Stage II (code 585.2). When the GFR falls below 90, patients will start to experience additional signs or symptoms. Patients will start to develop higher blood pressures, or if they already have hypertension, their blood pressure may be increasingly difficult to control without a diuretic. They also begin to have trouble excreting water and sodium, and may develop hyponatremia.

Stage III (code 585.3). When the GFR drops below 60, patients start having more problems with their metabolism. They start having trouble absorbing or excreting phosphorus in the urine, which leads to increases in parathyroid hormone levels. When phosphorus is not excreted normally, the parathyroid glands start elevating their level to try to facilitate that process.

Stage IV (code 585.4). When the GFR dips below 30, patients start having a lot more trouble with their calcium metabolism because their phosphorus level starts rising. Their calcium level then drops, which stimulates their parathyroid glands, which triggers even more hyperparathyroidism. This leads to problems with a patient’s inability to get rid of body acids, and this leads to acidosis. These are the patients who present with volume overload.

Stage V (code 585.5). Once a patient starts to develop hyperkalemia due to a lower GFR, the patient’s GFR is probably less than 15. But note that drugs such as nonsteroidals and ACE inhibitors can cause hyperkalemia even at Stage I or II, particularly in diabetic patients. So when hyperkalemia is present in a patient not taking a drug that facilitates it, this is a clear indicator that the patient is at an advanced stage of CKD, Huff said. Itching when there is no other identifiable cause is another hallmark of early uremia, meaning that the patient may be approaching end stage renal disease.

End stage renal disease (ESRD) (code 585.6). This term applies to those people with CKD who need renal replacement therapy, meaning either dialysis or renal transplant. Patients with ESRD may experience all of the aforementioned symptoms as well as nausea, vomiting, anorexia, and changes in mental status.

“I want to caution you that the GFR will vary when there are factors such as heart failure or dehydration,” Huff said. “If we have a patient who has CKD and they come in dehydrated with a GFR of 53, but after hydration their GFR came up to over 70, you would want to use the GFR of 70 to determine the stage of CKD.”

Recognize common complications

When coding for patients with CKD, be aware of common complications, two of which are volume overload and heart failure.

“It’s very important to note how we code these because if you have a patient who presents with volume overload and there is mention of heart failure, then you really don’t code volume overload,” said Huff, who explained that in this case you would only report the heart failure code (428 category). “[Volume overload] is considered integral to the heart failure, unless the physician specifically unlinks these two conditions.”

Hyperkalemia (code 276.7) is also a common complication related to CKD. Physicians treat mild hyperkalemia with Kayexelate and by correcting acidosis if present. If the patient shows EKG evidence of hyperkalemia (i.e., peak “T” waves, widening of QRS complex), the physician will treat the patient more emergently with telemetry, glucose and insulin administration, and dialysis, Huff said.

Hypocalcemia (code 275.41, unless directed otherwise by ICD-9-CM) and hyperphosphatemia (code 275.3) are also common manifestations in patients with CKD. These conditions can sometimes make removal of the parathyroid glands necessary because of the development of secondary hyperparathyroidism of renal origin (code 588.81) or tertiary hyperparathyroidism (code 252.08).

Finally, consider uremia (code 585.x for chronic uremia; code 586 for unspecified), which is a clinical syndrome indicating a sudden increase or buildup of the products of metabolism in the body (e.g., urea), resulting in the need for dialysis. People with uremia can also experience volume overload, heart failure, or acidosis, but these issues can also occur independent of a person with acute uremic syndrome, Huff said. Code separately each of these conditions (e.g., report hyperkalemia as an additional diagnosis).

Some of the long-term complications for patients with CKD include:

  • Anemia of chronic renal failure
  • Hyperparathyroidism (renal and tertiary)
  • Renal osteodystrophy
  • Dementia
  • Calciphylaxis

Note that this last complication, calciphylaxis, can be catastrophic, Huff explained. “When you start to have deposits of calcium in the blood vessels of the dermis, this can lead to infarctions of the skin and subcutaneous areas.”

Examine code assignment and sequencing

When considering codes for chronic renal failure, take a close look at two causes of CKD: Hypertension and nephrotic syndrome in people with diabetes.

“In ICD-9, there is an assumption that there’s a cause and effect relationship in people with hypertension and renal disease,” Huff said. While coders may assume the link between these two conditions, this is not the case for those with nephrotic syndrome and chronic renal failure.

Codes for primary hypertension are in category 403 or 404. Also assign the appropriate code for the specific stage of the renal disease. For secondary hypertension with renal disease, refer to code category 405.

For people who have nephrotic syndrome and diabetes, this is usually a clear indicator that the patient has diabetic nephropathy as opposed to some other cause such as hypertension. However, note that in this case, the physician must state a link between the CKD and the diabetes in the documentation, Huff said.

Refer to the following codes:

  • 249.4x, 585.x, specific pathological lesion
  • 250.4x, 585.x, specific pathological lesion

With regard to sequencing, CKD is a chronic disease so you would rarely sequence this as the principal diagnosis. However, CKD would be appropriate as the principal diagnosis in the following scenarios:

  • Hypertensive CKD with admission for blood pressure control
  • Initial diagnosis and cause of CKD unknown
  • Admission for preparation of dialysis but dialysis is not performed
  • Admission for uremic pericarditis and neuropathy

More typically, when a physician admits a person with CKD, the physician is treating a complication or a manifestation of the CKD. So coders more commonly assign the following as the principal diagnosis for patients with CKD:

  • Volume overload (not due to congestive heart failure [CHF])
  • CHF
  • Hyperkalemia
  • Hyperparathyroidism
  • Complications of dialysis process
  • Complications of catheter/fistula

Keep in mind that there are certain elements about which coders commonly query physicians. Coders often have to clarify whether the patient has only CKD or whether he or she has acute on chronic kidney disease. Also, it’s sometimes necessary to ask the physician to state the stage of CKD.

Editor’s note: Access HCPro’s November 9, 2010, audio conference, “Acute and Chronic Renal Failure Documentation: Understand the Clinical Indicators for Querying and Coding Accuracy” to learn more about acute kidney injury and the RIFLE classification. E-mail your questions to Managing Editor Doreen V. Bentley, CPC-A, at dbentley@hcpro.com.

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