Extended criteria (experimental). This is the broader ten-condition engine, kept as a secondary area. It shows ICD-10-CM codes and illustrative grouping effects for CDI staff. The primary surface is Before you sign (kidney, measurement only). All extended pages.

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Vera Penhallow: Hyponatraemia

ENC-00173 · 58F · Pulmonology · admitted Tue Nov 10, 2026 09:56 PM · in hospital · attending Dr. Rosalind Quillan · resident Dr. Noor Halvorsen

Specificity gap Criteria met Open In hospital: concurrent review Resident note awaiting attending cosign

Criteria support Hyponatraemia (profound) (E87.1); no corresponding diagnosis is documented.

Documented vs supported

Documented: not documented
Criteria support: Hyponatraemia (profound) · E87.1 Hypo-osmolality and hyponatremia
Outcome: Sodium below 135 on 4 values (lowest 124, profound) with treatment ordered
Rule: Hyponatraemia v2026.11-1
Published source: Clinical practice guideline on diagnosis and treatment of hyponatraemia (Spasovski et al., Eur J Endocrinol 2014;170:G1-G47) (2014), Classification by biochemical severity: mild 130-135, moderate 125-129, profound <125 mmol/L · source (checked 2026-11-14)

Effect if the clinician agrees (illustrative)

Change: add E87.1
Secondary-diagnosis level: — → CC
MS-DRG (illustrative): 191 Chronic obstructive pulmonary disease with CC → 191 Chronic obstructive pulmonary disease with CC
Relative weight: 0.8430 → 0.8430 (+0.0000)
Codes before: J44.1, I50.20, R09.02, K21.9, E11.9, E78.5
Codes after: J44.1, I50.20, R09.02, K21.9, E11.9, E78.5, E87.1

All open gaps on this encounter together: MS-DRG 191 → 190 (RW +0.2647).

CC/MCC status, CC exclusions (subset) and relative weights from the public CMS FY2026 IPPS final rule tables (5, 6I, 6J, 6K). This is not a grouper and not a payment estimate. Queries never mention any of this.

Severity documentation index change SIMULATED

0.5 points

SIMULATED: Illustrative severity weights (MCC = 1.0, CC = 0.5, non-CC = 0) summed over secondary diagnoses; not a validated risk-adjustment model and not a measured effect.

Evidence

Structured values are read by code from the cited rows. Note facts are shown only when the model's quote was found verbatim in the note.

Evidence (each item cited to a source row or a quoted span)
Input	Value	Source
Lowest serum sodium this stay (mmol/L)	124.0	sodium 124 mmol/L · lab LAB-005933 · 2026-11-11 05:00
Number of sodium values below 135	4	sodium 126 · lab LAB-005932 · 2026-11-10 22:56 sodium 124 · lab LAB-005933 · 2026-11-11 05:00 sodium 125 · lab LAB-005934 · 2026-11-12 05:00 sodium 128 · lab LAB-005935 · 2026-11-13 05:00
Fluid restriction, salt tablets, hypertonic saline or a vaptan ordered	True	fluid restriction 1.2 L/day · order ORD-000152 · 2026-11-11 00:56 sodium chloride 3% 100 mL IV · med MED-000691 · 2026-11-11 01:56

Rule trace (inputs, thresholds, outcome)

Rule trace (rule hyponatremia v2026.11-1; evaluated in order, first true outcome wins; "unknown" = missing input)
Step	Expression	Inputs and thresholds read	Result
derived: severity	`case(na_min < t.profound, 'profound', na_min < t.moderate, 'moderate', na_min < t.low, 'mild', 'none')`	na_min=124.0, t.low=135, t.moderate=130, t.profound=125	profound
outcome: met	`na_min < t.low and na_low_count >= t.repeat and na_treated`	na_low_count=4, na_min=124.0, na_treated=True, t.low=135, t.repeat=2	true

Documentation query

Title and question drafted by model clockworks-mock (audit entry #2293); clinical indicators and answer options assembled by code from the rule and the record.

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DOCUMENTATION QUERY (draft)
Title: Clarification request: electrolyte documentation
Encounter: ENC-00173   Patient: Vera Penhallow   To: Dr. Rosalind Quillan

Clinical indicators from the health record:
- sodium 124 mmol/L (2026-11-11 05:00) [lab LAB-005933]
- sodium 126 (2026-11-10 22:56) [lab LAB-005932]
- sodium 125 (2026-11-12 05:00) [lab LAB-005934]
- sodium 128 (2026-11-13 05:00) [lab LAB-005935]
- fluid restriction 1.2 L/day (2026-11-11 00:56) [order ORD-000152]
- sodium chloride 3% 100 mL IV (2026-11-11 01:56) [med MED-000691]

Question:
Based on your clinical judgement and the indicators above, can a related diagnosis be documented?

Response options (select one or write your own):
( ) Hyponatremia (please specify cause, if known)
( ) Other (please specify): ____________
( ) Unable to determine

Please respond based on your independent clinical judgement. Any response, including "unable to determine", is acceptable. This query and your response are kept as part of the health record.

Other findings on this encounter

Heart failure · Specificity gap Documented “systolic heart failure” (I50.20); criteria support the more specific Acute on chronic systolic (HFrEF) heart failure (I50.23).
Acute respiratory failure · Specificity gap Documented “hypoxemia” (R09.02); criteria support the more specific Acute respiratory failure with hypoxia (J96.01).

History

Audit entries for this finding (newest first)
Seq	When (UTC)	Actor	Action	Entities	Decision / reason	Model / hashes
2293	2026-11-14T20:57:26	system:llm system	`llm.call`	ENC-00173, ENC-00173.hyponatremia	—	clockworks-mock mock-1/exactdx.draft_query@1 prompt 300e15d9f73a output 1529a3e2b70e entry 241951f2ac5c
1467	2026-11-14T19:24:32	system:llm system	`llm.call`	ENC-00173, ENC-00173.hyponatremia	—	clockworks-mock mock-1/exactdx.draft_query@1 prompt 300e15d9f73a output 1529a3e2b70e entry 34995b6ae769
725	2026-11-14T18:29:07	system:llm system	`llm.call`	ENC-00173, ENC-00173.hyponatremia	—	clockworks-mock mock-1/exactdx.draft_query@1 prompt 300e15d9f73a output 1529a3e2b70e entry e6e9eae480c1