29th May 2025

Diagnosis

As in DKA, there is normally a trigger to HHS, most commonly infection but any condition that can place the body under stress. Several medications including corticosteroids, diuretics and atypical antipsychotics may trigger HHS. In contrast to DKA, HHS isn’t commonly seen on diagnosis with T2DM.  The symptoms relate to dehydration and any underlying cause:

• Tachycardia with a weak, low-volume pulse. Patients may have palpitations or chest pain if there is a cardiogenic cause.
• Hypotension, reduced skin turgor, reduced capillary refill time, cool and clammy peripheries if severely dehydrated.
• At first polyuria and then oliguria as dehydration worsens.
• Focal neurological signs, reduced consciousness, delirium and coma.
• Signs of infection or sepsis such as fever, hypotension, tachycardia etc.
• Signs of cardiovascular cause such as chest pain or palpitations.

The diagnostic criteria for HHS is a plasma glucose >600mg/dL and plasma osmolarity >320mOsm/L without the presence of ketoacidosis. There is often derangement of electrolytes and their correction is an important part of the management of HHS:

• Pseudohyponatraemia – due to intravascular dilution.
• Hyper/hypokalaemia – decreased insulin can cause the movement of potassium out of cells and into the vasculature. However, as HHS progresses potassium is increasingly lost in the urine.
• Hyperphosphataemia – due to muscle breakdown.
• Hypomagnesaemia – due to intravascular dilution and urinary loss.
• Ketones and bicarbonate – will be normal due to a lack of ketogenesis and normal pH.

Other blood results that may be noted are an increase in creatinine and BUN due to a prerenal azotaemia AKI. White blood cells and acute phase reactants may be raised even in the absence of infection as part of a stress response.