Week 12 - hyponatraemia, nephrotic syndrome, obesity, obstructive sleep apnea Flashcards
what are the normal sodium levels
135-145mmol/L
what are the types of hyponatraemia
Hypovolaemic
Euvolaemic
Hypervolaemic
Iso-osmolar
Hypertonic
what is hypovolaemic hyponatraemia due to
typically due to excess sodium loss
how is SIADH related to hyponatraemia
persistent release of ADH leading to water retention
what kind of hormonal insufficiency leads to hyponatraaemia
Addison’s
Hypothyroidism
Pregnancy – HCG ‘sets’ osmostat lower by 5 mmol/L
why do we correct sodium level slowly
to avoid central pontine myelinolysis
what are the common interventions for hyponatraemia
Fluid restriction to 800mls daily (or at minimum to less than urine output) – Used for oedematous states (heart and liver failure), SIADH, primary polydipsia and advanced renal failure
Cease any implicated medications
Isotonic or hypertonic (3%) saline – if true volume depletion (removes stimulus for ADH release) or adrenal insufficiency (replaces Na+ lost from kidneys)
ADH antagonist
when does nephrotic syndrome occur
when the basement membrane in the glomerulus becomes highly permeable to protein, allowing proteins to leak form the blood into the urine.
in who is nephrotic syndrome most common
in children between the ages of 2 and 5
how does nephrotic syndrome usually present
with frothy urine, generalised oedema, and pallor
what is the classic triad of nephrotic syndrome
Low serum albumin
High urine protein content (>3+ protein on urine dipstick)
Oedema
what are the three other features that occur in patients with nephrotic syndrome
Deranged lipid profile, with high levels of cholesterol, triglycerides and low density lipoproteins
High blood pressure
Hyper-coagulability, with an increased tendency to form blood clots
what are most cases of nephrotic syndrome due to
> 80% of cases are due to glomerulonephrotis
what happens in this syndrome
there is damage to the podocytes.
It was once thought that this allowed albumin to leak out into the tubule, thus causing proteinuria and hypoalbuminemia, and leading to reduced plasma oncontic pressure and peripheral oedema. The damage to the podocytes was thought not to be significant enough to allow RBC’s through the gaps thereby rendering haematuria unlikely. Recently, this theory has come under scrutiny as it has been discovered that the aforementioned situation does not cause a change in oncotic pressure, confirming the presence of an alternative pathology causative of oedema.
what are the primary causes of nephrotic syndrome that are diagnoses of exclusion that are only made if secondary causes cannot be found
Minimal change disease (MCD)
Focal segmental glomerulosclerosis
Membranous nephropathy
what are the secondary causes - note that these fall into the same three cateogries as the primary causes
Membranous nephropathy (MN) – Hep B, SLE, diabetes M, sarcoidosis, syphilis, malignancy
Focal segmental glomerulosclerosis –HIV, obesity, diabetes M, hypertensive nephrosclerosis
Minimal change disease –drugs, malignancy, particularly Hodgkin’s lymphoma
what does nephrotic syndrome increase the risks of
increased susceptibility to infection - partly due to loss of immunoglobulin in the urine
also increases the risk of thromboembolism and hyperlipidaemia
what are the investigations for nephrotic syndrome
same carried out in glomerulonephritis
check cholesterol as part of confirming the presence of hyperlipidaemia
why do you order a renal biopsy for adults
because in children, the main cause is minimal change GN, and steroids are first line treatment.
therefore, in children biopsy is necessary only if pharmaceutical intervention fails to improve the situation
what is the management of nephrotic syndrome usually based on
involves treatment of the underlying condition which is usually GN
therefore, fluid management and salt intake restriction are priorities
what medications is the patient usually given in nephrotic syndrome
furosemide along with an ACE inhibitor and/or angiotensin II receptor antagonist
prophylatic heparin is given if the patient is immobile.
what is hyperlipidaemia treated with
a statin
describe the hypercoagulant state seen in nephrotic syndrome and how this presents and is treated
can be a risk factor for renal vein thrombosis
it presents as loin pain, haematuria, palpable kidney and sudden deterioration in kidney function
this should be investigated with Doppler USS, MRI or renal angiography
what does diagnosis of PCOS require
Diagnosis requires 2 of the below (and thus can be clinical – without the need for investigations):
- Signs of hisutism
- Oligomenorrhoea (<9 periods per year)
- >12 peripheral ovarian follicles OR ovarian volume >10mls on USS
what is the first line medication approved for weight loss
ortlistat
reduces the absorption of fat by inhibiting pancreatic and gastric lipases
which drug is thought to suppress hunger
phentermine (duromine and metermine)
what is obstructive sleep apnoea caused by
a collapse of the pharyngeal airway
what is OSA characterised by
episodes of apnoea during sleep, where the person stops breathing periodically for up to a few minutes
what are the risk factors for obstructive sleep apnoea
Middle age
Male
Obesity
Alcohol
Smoking
what are the features of obstructive sleep apnoea
Episodes of apnoea during sleep (reported by their partner)
Snoring
Morning headache
Waking up unrefreshed from sleep
Daytime sleepiness
Concentration problems
Reduced oxygen saturation during sleep
what can severe episodes of obstructive sleep apnoea cause
Severe cases can cause hypertension, heart failure and can increase the risk of myocardial infarction and stroke.
what is the Epworth Sleepiness Scale used to do
used to assess symptoms of sleepiness associated with obstructive sleep apnoea
what is the top tip for OSCEs and OSA
TOM TIP: If interviewing someone you suspect has obstructive sleep apnoea, ask about daytime sleepiness and occupation. Daytime sleepiness is a crucial feature that should make you suspect obstructive sleep apnoea. Patients that need to be fully alert for work, for example, heavy goods vehicle operators, require an urgent referral and may need amended work duties whilst awaiting assessment and treatment.
what is the management of patients with obstructive sleep apnoea
require referral to an ENT specialist to perform sleep studies.
this involves the patient sleeping in a labarotory whilst staff monitor their oxygen saturation, heart rate, respiratory rate and breathing to establish any episodes of apnoea and the extent of their snoring
what is the first step of management in OSA
to correct reversible risk factors by advising them to stop drinking alcohol, smoking or lose weight
what is the second step in management of OSA
to use CPAP machine that provides continuous pressure to maintain the patency of the airwau
is surgery an option in obstructive sleep apnoea
yes.
this involves quite significant surgical reconstruction of the soft palate and jaw.
the most common procedure is a uvulopalatopharyngoplasty (UPPP).
