Acid-Base Disorders in CDI: Lactic Acidosis Query and ICD-10-CM Coding Guidance

Clinical Scenario: Acid-Base Imbalance in Crohn’s Disease

H&P: 51-year-old female with Crohn’s disease, morbid obesity, and a BMI of 42 presents from home in a private vehicle with 4 days of fever, severe abdominal pain, diarrhea, and nausea and vomiting.

Patient History, Vitals, and Clinical Findings

PMH: Hypertension, Crohn’s disease, and CKD Stage 3a with a baseline creatinine of 1.2

Home Medications: Stelera 90 mg SQ every 8 weeks (last dose 6 weeks ago), Prednisone 20 mg PO daily, Metoprolol 50 mg PO BID, and Lisinopril 20 mg PO daily

Vitals: B/P 99/56, HR 89, Temp 100.8, RR 18, Pulse ox 96% on room air

PE: Abdomen TTP, scant dark urine

Labs: Lactic Acid 4.2, WBC 18.5, Creatinine 1.5, CRP 105. Repeat lactic acid after fluid bolus 3.0 and 1.5.

CT: Abdomen revealing small-bowel wall thickening, mesenteric inflammatory stranding, and mesenteric adenopathy, partial small bowel obstruction. Impression: Crohn’s disease with partial obstruction

Treatment Course and Discharge Summary

Consult: GI consulted, NGT placed, started IV prednisone to be tapered to PO once pain subsides and having bowel movements again.

Discharge Summary: Crohn’s flare with partial small bowel obstruction. Treated with NGT tube, IV prednisone, pain medication, 2 L normal saline bolus & normal saline continuous IV @ 75 ml/hr. Patient is tolerating PO intake and having normal bowel movements. Outpatient GI follow-up in 1 week.

Discharge Medication: Prednisone increased to 40 mg PO daily, resume home medications of Metoprolol 50 mg PO BID, and Lisinopril 20 mg PO daily, and normal Stelera injection in 10 days.

CDI Query Opportunity: Lactic Acidosis

Question: Are there query opportunities based on the scenario stated above?

Discussion: The patient has exhibited the following risk factors and clinical indicators: 4 days of abdominal pain, diarrhea, and nausea & vomiting. Lactic Acid 4.2 with repeat lactic acid after fluid bolus 3.0 and 1.5. Crohn’s disease with partial small bowel obstruction and CKD stage 3a.

Diagnostic Criteria for Lactic Acidosis

Lactic acid > 4

Lactic Acid > 2 plus pH < 7.35

Lactic Acid > 2 plus Anion gap > 12

Treatment Indicators Supporting Lactic Acidosis

Normal saline IV fluid bolus 2,000 ml

Normal saline IV continuous rate 75 ml/hr

UASI Recommends: Query for Lactic Acidosis

Impact of Documentation on Coding and DRG

Documentation without clarification:

Principal Diagnosis: K50.012 Crohn’s disease of small intestine with intestinal obstruction

Secondary Diagnosis: E66.01 Morbid obesity, Z68.41 BMI 40.0-44.9 adult

Working DRG: 386 Inflammatory bowel disease with CC

RW: 0.9898

GLMOS: 3.4

SOI/ROM: 1/1

Documentation with clarification:

Principal Diagnosis: K50.012 Crohn’s disease of small intestine with intestinal obstruction

Secondary Diagnosis: E66.01 Morbid obesity, Z68.41 BMI 40.0-44.9 adult, E87.20 Acidosis, unspecified

Working DRG: 386 Inflammatory bowel disease with CC

RW: 0.9898

GLMOS: 3.4

SOI/ROM: 2/2

CDI Educational Tips for Acid-Base Disorders

Acidosis is classified to code E87.20. Inclusion terms are lactic acidosis and metabolic acidosis.

E87.20 provides a CC as a secondary diagnosis.

The treatment of metabolic acidosis and alkalosis depends entirely on its cause. The underlying cause should also be treated.

Conditions often associated with acid/base imbalance include diarrhea, poisoning (metabolic acidosis), vomiting, dehydration (metabolic alkalosis), sepsis (elevated lactate), and COPD (respiratory acidosis).

Interpreting Lactate Levels and Clinical Significance

An elevated lactate/lactic acid does not necessarily indicate lactic acidosis which requires elevated lactate in addition to acidosis (pH<7.35). Lactate levels < 2.0 are normal, and transient slight elevations are often not clinically significant. For example, a slightly elevated lactate of 2.2 on admission for which the lactate level is simply repeated.