Endocrinology - HHS

Question 1

What is HHS? What are the 3 characteristic features?

Answer 1

Hyperosmolar hyperglycaemic state

1. severe hyperglycaemia (>30 mmol/L) without sig. hyperketonaemia (<3 mmol/L) or acidosis (pH >7.3)
2. hyperosmolarity (>320 mOsmol/kg)
3. hypovolaemia

Question 2

Why does HHS occur? Give examples.

Answer 2

Occurs in people with T2DM (typically elderly): very high blood glucose levels develop due to combination of illness, dehydration and inability to take normal diabetes medication due to effects of illness.

E.g.

1) intercurrent or co-existing illness: MI, pneumonia, stroke, AKI, hyperthyroidism, etc.
2) medication-induced: diuretics, beta-blockers, CCS, anti-psychotics, prednisolone, alcohol, cocaine, etc.
3) diabetes-related: 1st presentation of DM or poor control/non-compliance

Question 3

what are the downstream effects of hyperglycaemia? what are the possible complications?

Answer 3

Hyperglycaemia causes an osmotic diuresis… dehydration and hyperosmolarity… osmotic shift of water into intravascular compartment… intracellular dehydration.

Complications:

• vascular: MI, stroke, organ infarction, DVT and PE
• DIC
• multi-organ failure and ARDS
• iatrogenic complications of rehydration adne electrolyte management, e.g. cerebral oedema, central pontine myelinosis
• foot pressure ulcers (examine feet daily)

Question 4

describe the early and late symptoms of HHS

Answer 4

Usually develops over days-wks.

Early:

• polydipsia and polyuria
• generalised weakness
• leg cramps
• visual impairment
• +/- nausea and vomiting (occur less often than in DKA)

Late:

• confusion, lethargy
• focal neurological symptoms, e.g. unilateral weakness or hemisensory abnormalities
• seizures (25%) - may be generalised, focal, mov.-inducted or myoclonic-jerk type
• coma (rare, 10%)

Question 5

describe the signs of HHS.

Answer 5

• signs of dehydration, e.g. dry mucous membranes, reduced skin turgor
• appear ill and exhausted
• evidence of disorientation or confusion
• cranial nn. dysfunction, e.g. visual field deficits, nystagmus
• tachycardia, hypotension, increased resp. rate +/- decreased SaO2

Question 6

which investigations would you perform on someone with suspected HHS?

Answer 6

Bloods:

• plasma glucose: increased
• serum osmolarity: increased, >320 mOsmol/kg
• FBC and CRP
• UandE: ?dehydration/pre-renal AKI, deranged Na+ and K+ levels
• CK: ?rhabdomyolysis
• troponin I and T: if MI suspected
• blood cultures: ?sepsis

Bedside tests:

• capillary blood glucose: >30 mmol/L
• urine dipstick: glycosuria with normal or only slightly raised ketones
• urine MandC: ?UTI
• ECG: ?MI, ?arrythmias
• CXR: ?chest infection
• CT/MRI head: if reduced consciousness or focal neurology

Question 7

how would you manage a pt with HHS?

Answer 7

Continuous SaO2, ECG and BP/HR monitoring. Catheterise to monitor UO and for urinalysis. Measure or calculate osmolality frequently to monitor treatment response.

1. Fluid resuscitation with IV 0.9% saline. encourage oral fluid intake as soon as possible. Rate of plasma Na+ decrease should not exceed 10 mmol/L in 24 hrs.
2. Low dose IV insulin (0.05 units/kg/hr) started once blood glucose no longer falling with IV fluids alone, OR immediately if significant ketonaemia.
3. ID and treat precipitant.

Question 8

how do you calculate serum osmolality?

Answer 8

Osmolality = 2Na + glucose + urea