Does HHS Definition Require Change in Mentation?
No, altered mental status is not an absolute requirement for diagnosing hyperosmolar hyperglycemic state (HHS), though it is commonly present and included in diagnostic criteria as a clinical feature rather than a mandatory criterion.
Diagnostic Criteria for HHS
The formal diagnostic criteria for HHS focus on metabolic parameters, not mental status 1:
- Blood glucose ≥600 mg/dL 1
- Arterial pH ≥7.30 1
- Serum bicarbonate ≥15 mEq/L 1
- Effective serum osmolality ≥320 mOsm/kg H₂O 1
- Small or absent ketones (urine and serum) 1
Mental Status as a Clinical Feature
While altered mental status is characteristic of HHS, it exists on a spectrum rather than as a binary requirement 1:
- Mental status can vary from full alertness to profound lethargy or coma, with altered consciousness being more frequent in HHS than in DKA 1
- The degree of mental obtundation typically correlates with the severity of hyperosmolarity 1
- Stupor/coma is listed in diagnostic tables as the typical presentation, but this reflects common clinical presentation rather than mandatory criteria 1
Important Clinical Context
The distinction between diagnostic criteria and clinical presentation is critical 1:
- In pediatric protocols, HHS is defined as requiring "altered mental status or severe dehydration" (note the "or"), indicating that mental status change alone is not mandatory if severe dehydration is present 1
- Recent literature consistently describes altered mental status as a "neurologic abnormality" that is "most commonly" present but uses language suggesting it is expected rather than required 2
- Treatment protocols focus on resolving "mental obtundation and hyperosmolarity," suggesting these are parallel treatment goals rather than mental status being definitional 1
Practical Implications
In clinical practice, suspect HHS based on metabolic criteria even if mental status is preserved 1:
- Patients meeting metabolic thresholds (glucose ≥600 mg/dL, osmolality ≥320 mOsm/kg) warrant HHS management regardless of alertness 1
- The absence of altered mental status does not exclude HHS diagnosis when other criteria are met 1
- Monitor for mental status changes during treatment as they may develop or worsen with rapid osmolality shifts 3