Definition

A precise definition of HHS does not exist and would be inappropriate, but there are characteristic features that differentiate it from other hyperglycaemic states such as DKA.

These are:

• Hypovolaemia
• Marked hyperglycaemia (30 mmol/L or more) without significant hyperketonaemia (Less than 3 mmols/L or Acidosis pH>7.3, bicarbonate >15 mmol/L)
• Osmolality usually 320 mosmol/kg or more 

Learning bite

A mixed picture of HHS and DKA may occur.

People with HHS are generally older, but increasingly, as the diabetes pandemic crosses generational boundaries, it may be seen in young adults and even children as the first presentation (Fourtner 2005).

In HHS there is usually no significant ketosis/ketonaemia (ketones <3 mmol/L), though a mild acidosis (pH greater than 7.3, bicarbonate greater than 15 mmol/L) may accompany the pre-renal failure. Some patients have severe hypertonicity and ketosis and acidosis (mixed DKA and HHS). This presumably reflects insulin deficiency, due to beta cell exhaustion as a result of temporary glucotoxicity. These patients may require a modification of this treatment guideline to take into account which aspect predominates.

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