HHS Flashcards
What does HHS stand for
Hyperosmolar Hyperglycaemic State (HHS)
HHS is a medical emergency that occurs in patients with what type of diabetes mellitus
Type 2 diabetes mellitus
HHS is charactersied by?
Characterised by profound hyperglycaemia, hyperosmolality and volume depletion in the absence of significant ketoacidosis
What is the onset of HHS like
Occurs insidiously over several days to weeks
Features get worse as there is more renal water loss and higher levels of hyperglycaemia
What is the mortality associated with HHS
High mortality (5-15%)
Describe the pathophysiology of HHS
The relative lack of insulin (not enough to produce ketones) is coupled with a rise in counter-regulatory hormones leading to a profound rise in glucose (hyperglycaemia)
Hyperglycaemia results in osmotic diuresis with associated loss of sodium and potassium.
This is because the proximal tubules within the kidneys only have a certain capacity for reabsorption of glucose thus when this limit is reached the remaining glucose pass through causing diuresis
This severe volume depletion results in profound dehydration and reduced circulating volume – hyperosmolarity and hyperglycaemia
The hyperosmolarity (typically > than 320 mosmol/kg), resulting in hyperviscosity of blood – which increases the risk of arterial and venous thrombosis e.g. DVT
HHS is characterised by profound hyperglycaemia, hyperosmolality and volume depletion in the absence of significant ketoacidosis.
What happens in the body to cause the hyperglycaemia
The relative lack of insulin (not enough to produce ketones) is coupled with a rise in counter-regulatory hormones leading to a profound rise in glucose (hyperglycaemia)
HHS is characterised by profound hyperglycaemia, hyperosmolality and volume depletion in the absence of significant ketoacidosis.
What happens in the body to cause the hyperosmolality and volume depletion
HHS is characterised by hyperglycaemia
The hyperglycaemia results in osmotic diuresis with associated loss of sodium and potassium.
This is because the proximal tubules within the kidneys only have a certain capacity for reabsorption of glucose thus when this limit is reached the remaining glucose pass through causing diuresis
This severe volume depletion results in profound dehydration and reduced circulating volume – hyperosmolarity and hyperglycaemia
The hyperosmolarity (typically > than 320 mosmol/kg), resulting in hyperviscosity of blood – which increases the risk of arterial and venous thrombosis e.g. DVT, PE
Why are patients with HHS at a high risk of developing thrombosis
Patients with HHS have a hyperviscosity of their blood - due to the hyperosmolarity
Name the precipitants of HHS
New diagnosis of type 2 diabetes
Poor treatment concordance in T2DM
Infection
High dose steroids
MI
Vomiting
Stroke
Describe the onset of clinical features for HHS
The onset of features is usually insidious, developing over days to weeks as there is an increase in renal water loss and higher levels of hyperglycaemia
Name some of the early features of HHS
Polyuria
Polydipsia
Nausea
Dehydration e.g. dry mucous membranes, sunken eyes, reduced capillary refill, decreased skin turgor
Weight loss
Hypotension
Decreased urine output
Name some of the late features of HHS
Altered mental status
Seizures
Shock
Coma
How is HHS diagnosed
Diagnosed based on the presence of characteristic features:
- Severe hyperglycaemia (glucose >30 mmol/L)
- Hyperosmolality (serum osmolality > 320 mOsm/Kg)
- Absence of acidosis
- Mild/absent ketogenesis (urine: 1+ or trace; blood < 3 mmol/L)
These should be taken in context with the clinical state of the patient e.g. dehydrated
HHS vs DKA
Both are characterised by hyperglycaemia Unlike DKA, the hyperglycaemia in HHS is not accompanied by significant acidosis (pH > 7.3; Bicarb > 15 mmol/L) or ketosis (ketones > 3mmol/L)
This is because in HHS, the presence of endogenous insulin production is sufficient to “switch off” ketone production preventing the ketoacidosis
