There is almost no difference between ICD-9 and ICD-10 when it comes to coding chronic kidney disease (CKD). More dead wood was cleaned out of ICD-9 and a bit more useful detail added in ICD-10.
On the other hand, there are roughly half again as many anemia codes in ICD-10 as in ICD-9. Most of these are a straightforward expansion of detail, and if you provide documentation for the available detail in the codes, there is nothing tricky about using them. Most of these new detailed codes are for the rarer anemias. The most common anemias can be documented and coded just as they are now in ICD-9. And of course, the expanded classifications always contain an unspecified code for times when the detail is unavailable, and not worth your patient’s healthcare dollars to get.
Chronic Kidney Disease
The ICD-9 CKD codes have been updated in recent years to imitate CKD as classified in ICD-10, so they pretty much match. Here are the bread-and-butter CKD codes in ICD-10.
N18.1 Chronic kidney disease, stage 1
N18.2 Chronic kidney disease, stage 2 (mild)
N18.3 Chronic kidney disease, stage 3 (moderate)
N18.4 Chronic kidney disease, stage 4 (severe)
N18.5 Chronic kidney disease, stage 5
N18.6 End stage renal disease
N18.9 Chronic kidney disease, unspecified
The ICD-9 codes are just like this, except they use roman numerals for the stages. Woohoo. Presumably the accepted correlations between CKD stage and glomerular flow rate (GFR) will stay the same. They are provided here for convenience:
CKD stage 1 = GFR > 90
CKD stage 2 = GFR 60-89
CKD stage 3 = GFR 30-59
CKD stage 4 = GFR 15-29
CKD stage 5 = GFR <15
Often these CKD stage codes are secondary codes, preceded on the record by a code for the underlying cause of CKD, usually a diabetes code or a hypertensive kidney disease code. In the case of hypertensive kidney disease, all those absurd “malignant” and “benign” hypertensive kidney disease codes in ICD-9 are left out of ICD-10. If you’re interested in more on that subject, I wrote about hypertension coding a few blogs ago in “80-20 Coding for ICD-10.” 
For patients with CKD as a manifestation of diabetes, ICD-10 has its own specific code, subdivided by type of diabetes. For example, the ICD-10 code below for type 1 diabetes with CKD replaces its less specific ICD-9 counterpart.
E10.22 Type 1 diabetes mellitus with diabetic chronic kidney disease
250.41 Diabetes with renal manifestations, type I [juvenile type], not stated as uncontrolled
In both ICD-9 and ICD-10, there are all kinds of anemia codes for specific populations — for example, newborns and pregnant women. When I refer to anemia here, I will stick to the codes that classify anemias occurring in the general population.
Anemias in chronic disease such as CKD or cancer can be documented just as they are for ICD-9. The code descriptions are identical. Same deal with anemia resulting from chemotherapy. However, three other causes of chronic anemia have expanded code detail in ICD-10: drug-induced anemias, anemias caused by vitamin or mineral deficiency, and metabolic disorders that cause anemia.
The ability to code a chronic anemia as drug-induced (other than chemotherapy induced, which has been around awhile) is new in ICD-10. For example, acquired hemolytic anemias, further specified as autoimmune or not, can also be coded according to whether they were drug-induced, if that is known and documented as such. Here are a couple of examples of ICD-9 codes and the ICD-10 codes that replace them.
283.0 Autoimmune hemolytic anemias
is replaced by
D59.0 Drug-induced autoimmune hemolytic anemia
D59.1 Other autoimmune hemolytic anemias
283.19 Other non-autoimmune hemolytic anemias
is replaced by
D59.2 Drug-induced nonautoimmune hemolytic anemia
D59.4 Other nonautoimmune hemolytic anemias
Vitamin B12 deficiency anemia codes have been updated and expanded. What used to be classified as pernicious anemia now has the fancier title D51.0 Vitamin B12 deficiency anemia due to intrinsic factor deficiency but still can be coded with pernicious anemia documented on the record. B12 deficiencies are further classified according to whether they are caused by hereditary absorption deficiency, other dietary deficiency or some other cause. The non-specific code is also available.
If documenting the exact cause of a B12 deficiency — even more so, if finding out the precise cause is a waste of your patient’s time and money since you are just going to treat them with vitamin B12 anyway — then have a ball and use the non-specific code. You aren’t likely to suffer any consequences here.
Other vitamin deficiency anemias have been similarly expanded, along with metabolic disorders that cause anemia, but these are rare enough to fall well below the 80/20 threshold for “mentionability.” The main thing to remember here is that for both CKD and anemia, documentation for ICD-10 codes is essentially unchanged compared to ICD-9.
Rhonda Butler is a senior clinical research analyst with 3M Health Information Systems. She is responsible for the development and maintenance of the ICD-10 Procedure Coding System since 2003 under contract to CMS, and for the development and maintenance of the ICD-10 General Equivalence Mappings (GEMs) and Reimbursement Mappings under contract to CMS and the CDC. She leads the 3M test project to convert the MS-DRGs to ICD-10 for CMS, and is on the team to convert 3M APR-DRGs to ICD-10. Rhonda also writes for the 3M Health Information Systems blog .