A primary function of queries is ensuring that coding is complete and accurately reflects the severity of the patient’s condition. Failing to code for diagnoses that are CCs or MCCs means the DRG assigned may not be the one that most appropriately reflects the resources required to care for the patient or their actual severity of illness or risk of mortality.
Since acute tubular necrosis is an MCC it is important for complete and accurate coding to identify if this diagnosis is suggested by clinical indicators when it is not specifically documented in the health record.
Recognizing an opportunity to query for acute tubular necrosis requires knowledge of its underlying pathophysiology and the clinical indicators suggesting its presence.
Acute tubular necrosis (ATN) is a type of acute kidney injury that occurs when kidney tubules are damaged. Kidney tubules are tube shaped structures that filter salts, excess fluid and waste from the blood as urine is formed.
Acute tubular necrosis has several causes, including reduced blood flow to the kidneys (ischemia), nephrotoxins and serious infections. The conditions that are most commonly associated with ATN are:
Some patients with ATN are asymptomatic, and the condition is only found through laboratory testing. If the condition is severe, symptoms may include:
Acute tubular necrosis is diagnosed through testing of the blood and urine. To establish a diagnosis of acute tubular necrosis, the patient should meet the criteria for Acute Kidney Injury (AKI) based on Kidney Disease Improving Global Outcomes (KDIGO) criteria:
If renal function returns within 72 hours acute kidney injury (AKI) is likely present rather than acute tubular necrosis (ATN).
Other abnormal lab values that indicate acute tubular necrosis include:
Treatment consists primarily of:
Dialysis may be required if patients do not respond to supportive care.
In healthy patients where the underlying condition is corrected and blood creatinine levels return to normal or near normal within 1 to 3 weeks, the prognosis for recovery is good. However, patients who survive acute tubular necrosis have an increased risk of developing chronic kidney disease.
Having an example to reference is helpful when first formatting a query for acute tubular necrosis. Review the case examples below to get a better idea of what this type of query might look like.
CASE 1:Patient admitted with uncontrolled diabetes type 2 with hyperosmolar nonketotic hyperglycemia. Noted to have AKI by the physician with creatinine elevation of 4.28 with a baseline of 1.5 to 1.7. Urinalysis showed hyaline casts were present Creatinine trended down to baseline on the 4th day. Chart Documentation:H&P 5/4@01:56: "Acute kidney injury. Dehydration... IV hydration was provided. Renally adjust medications, avoid nephrotoxic agents/dehydration/hypotension." Discharge Summary 5/6@12:52: "1. Please follow up with primary care provider within 1-2 weeks... Please repeat BMP and CBC in one week... Hyperosmolar nonketotic state... started on IV insulin with q 1 hour, CBG check and q 4 hour, BMPs... aggressive fluid resuscitation... Acute on chronic renal failure--CKD stage IIIb, Baseline creatinine 1.5–1.7... Secondary to volume depletion... Continue IV fluids>>improving" Query Initiated:Dear Dr. _______ - Acute kidney failure with acute tubular necrosis Risk Factors:66-year-old male with medical history significant for diabetes mellitus type 2, COPD, stroke, hypertension, CKD 3. Clinical Indicators:Labs:Creatinine:5/3-4.28(H) 5/3-UA: Hyaline cast Present. Rationale:Query for ATN is appropriate since creatinine took more than 72 hours to return to baseline and urinalysis showed the presence of hyaline casts. |
CASE 2:Patient admitted with pyoderma gangrenosum and acute kidney injury. Noted to have a creatinine elevation of 3.14 with a baseline of 1.4 – 1.7. Urine sodium was performed and was elevated at 103 and 108. Creatinine remained elevated for greater than 72 hours. Chart Documentation:Creatinine: 3/07-3.14-H, 3/08-2.62-H, 3/11-1.99-H, 3/13-1.98-H, 3/15-1.86-H, 3/18-2.07-H, 3/20-1.77-H Urine Sodium- 3/07-103, 3/13-108 H&P 3/07 14:57 pm- Pyoderma gangrenosum, acute on chronic. Acute kidney injury- Likely pre-renal given report of limited access to food/drink. IVF given. Trend Cr. Progress Note 3/15 10:52 am- Pre-renal, non-oliguric AKI: improving. Baseline Cr 1.2. Progress Note 3/21 07:22 am- AKI on CKD3. Creatinine 3.14 on admission (baseline 1.4-1.7), now improved to 1.77. . Prior renal US with medical renal disease. urine protein/albumin to cr ratio. outpatient referral to nephrology. Progress Note 3/23 07:34 am- AKI on CKD3 (resolved). Query Initiated:Dear Dr. ________ Based on your judgement and review of the clinical indicators below can you please clarify the diagnosis you are treating? The patient's clinical indicators include: Creatinine: 3/07-3.14-H, 3/08-2.62-H, 3/11-1.99-H, 3/13-1.98-H, 3/15-1.86-H, 3/18-2.07-H, 3/20-1.77-H Urine Sodium- 3/07-103, 3/13-108 H&P 3/07 14:57 pm- Pyoderma gangrenosum, acute on chronic. Acute kidney injury- Likely pre-renal given report of limited access to food/drink. IVF given. Trend Cr. Progress Note 3/15 10:52 am- Pre-renal, non-oliguric AKI: improving. Baseline Cr 1.2. Progress Note 3/21 07:22 am- AKI on CKD3. Creatinine 3.14 on admission (baseline 1.4-1.7), now improved to 1.77. . Prior renal US with medical renal disease. urine protein/albumin to cr ratio. outpatient referral to nephrology. Progress Note 3/23 07:34 am- AKI on CKD3 (resolved). Treatment- Creatinine monitoring, IVFs, Solumedrol, Water-oral rehydration 800ml every 8 hours Risk Factors- 67 yo Male with PMH of Cocaine Use, DVT, SVT, HCV, Anemia and levimasole-associated pyoderma gangrenosum presented with c/o RLE pain. Options provided:-- AKI on CKD with acute tubular necrosis present Rationale:Querying for ATN is appropriate since creatinine took more than 72 hours to return to baseline and urine sodium was greater than 40. |
References
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The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.