With the increased incidence and prevalence of kidney disease in the United States today, accurate classification of the severity and type of disease process is more important than ever. Since 1984, when slightly less than 100,000 patients nationwide suffered from kidney disease, the incidence has increased to more than 372,000 in 2002 and is projected to exceed 661,000 in 2010. To help track the variations in the disease process more closely and to reflect more current terminology, new and revised kidney disease ICD-9-CM codes were released, effective Oct. 1, 2005. It's important to note that not only should the coder understand the clinical definitions related to kidney disease, they should also know when to query the physician for clarification or further information when necessary.
The kidneys function by filtrating about 200 quarts of blood a day and eliminating about 2 quarts of waste products and extra water. The waste and extra water become urine, which flows through the ureters to the bladder and is eliminated through urination. Each kidney contains about a million nephrons, which are small units that perform the filtration process. Inside the nephron is a glomerulus, which is a small capillary that is entwined with a small urine-collecting tube called a tubule. It's the glomeruli and tubules that interact to perform the filtration process.
Chronic Kidney Disease
Most kidney diseases attack the nephrons, which cause them to lose their filtering capacity. The most common causes of kidney disease-diabetes and hypertension-involve a slow deterioration process that may take years before the damage is apparent. Gradual loss of kidney function called chronic kidney disease (CKD) is now indexed in ICD-9-CM to code 585. The terminology of code 585 has been changed from "chronic renal failure" to "chronic kidney disease (CKD)." A fourth digit subdivision has been added to represent the progressive stages of kidney disease (discussed below).
Kidney function is most often measured by a blood test called a Glomerular Filtration Rate (GFR), which is based on the amount of creatinine in the blood. Creatinine is a waste product in the blood that's created by the normal breakdown of muscle cells during activity. A healthy kidney will filtrate creatinine into the urine for elimination, but when a kidney isn't functioning well, the creatinine builds up in the blood. The creatinine is measured in terms of how many milligrams of creatinine are in one deciliter of blood (mg/dL). Because the creatinine levels can be variable and can be affected by the patient's diet, a GFR calculation is usually more accurate in determining decreased kidney function. Because the GFR uses the patient's creatinine value, along with age, weight and other values assigned for sex and race, it's typically more widely used today. The table above indicates GFR values for each stage of kidney disease, along with the corresponding ICD-9-CM diagnosis code.
Of course, diagnosis codes cannot be assigned on the basis of laboratory values alone. The physician must document the stage of kidney disease, but it's helpful for the coder to understand the disease process, which will help in communication or the query process with the medical staff.
In addition to the newly subdivided codes mentioned in the table, two additional codes in the 585 category are now available:
585.6 (End stage renal disease [ESRD]), which is a federal government defined term that indicates chronic treatment by either dialysis or transplantation. ESRD is a complete or near complete failure of the kidneys and without dialysis or a transplant, multiple and severe complications or death from accumulation of fluids and waste products in the body may result.
585.9 (CKD, unspecified). While this is a somewhat non-specific term, the most common assignment of this code will typically be for chronic renal insufficiency. This revision in indexing was also effective Oct. 1, 2005.
Coders should be aware the acute renal insufficiency continues to be indexed to code 593.9, Unspecified disorder of kidney and ureter. A new indexed entry is planned for Oct. 1, 2006; until then, code 593.9 should also be assigned for unspecified renal insufficiency. The fact that chronic renal insufficiency is now assigned to code 585.9 also means that if hypertension is documented on the same case, the cause-and-effect rules of ICD-9-CM dictate that the combination code from category 403 should be assigned instead of separate kidney disease and hypertension codes.
If a patient's encounter is for dialysis, code V56.0 (Extracorporeal dialysis) should be assigned as the first-listed diagnosis. Coders should also remember that if a patient has undergone kidney transplantation, code V42.0 (Kidney transplant status) should be assigned unless the documentation indicates a condition that affects the functioning of that transplanted organ. If the documentation indicates decreased or non-functioning kidney transplant, code 996.81 should be assigned.
Because CKD cases tend to be a high-volume service area for many facilities, coding staff should ensure that not only are they clear on the revised codes, but that the medical staff members are aware of the increased documentation required to ensure appropriate code assignment. Coders may also want to review Coding Clinic, 4th Quarter 2006, pp. 77-79. Test your knowledge with the quiz below:
1. A 66-year-old patient with end stage renal disease presents to the dialysis clinic for his regularly scheduled dialysis treatment. The appropriate diagnosis code(s) are:
a. 585.6, V56.0
b. V56.0, 585.6
2. A 73-year-old male patient is admitted with diabetic nephropathy and Stage V kidney disease. The medical record also indicates that the patient carries a diagnosis of hypertension. The appropriate diagnosis code(s) are:
a. 585.5, 250.40
b. 403.91, 250.40
c. 250.40, 585.5, 403.91
3. A 59-year-old female patient who is status post kidney transplant was admitted with a postoperative lymphocele that decreased kidney function. The patient underwent surgical treatment. The appropriate diagnosis code(s) are:
a. 457.8, V42.0
b. 996.73, E878.2
c. 996.81, E878.0, 457.8
d. V42.0, 457.8
This month's column has been prepared by Cheryl D'Amato, RHIT, CCS, director of HIM, and Melinda Stegman, MBA, CCS, manager of clinical HIM services at HSS, an Ingenix company (www.hssweb.com). HSS specializes in the development and use of software and e-commerce solutions for managing coding, reimbursement, compliance and denial management in the health care marketplace.
Coding Clinic is published quarterly by the AHA.
CPT is a registered trademark of the AMA.
Answers to CCS Prep!: 1. b. Code V56.0 (Extracorporeal dialysis) is a "first-listed only" code and should be assigned when the reason for the visit is for routine dialysis. Because the patient's kidney disease is specified as being end-stage, code 585.6 should be assigned; 2. c. ICD-9-CM coding guidelines dictate that the diabetes code be sequenced first and the manifestation code sequenced in a secondary position. Because the patient has Stage V kidney disease and a condition classifiable to a 585 category code and also hypertension, the combination code 403.91 should be assigned due to the cause-and-effect relationship implied in ICD-9-CM between chronic kidney disease and hypertension; 3. c. Because the kidney function was affected, the condition must be classified as a complication of the transplanted organ. Codes 996.81 and E878.0 are appropriate; code 457.8 is assigned as a secondary diagnosis for the lymphocele.