Week 12 - hyponatraemia, nephrotic syndrome, obesity, obstructive sleep apnea

Question 1

what are the normal sodium levels

Answer 1

135-145mmol/L

Question 2

what are the types of hyponatraemia

Answer 2

Hypovolaemic
Euvolaemic
Hypervolaemic
Iso-osmolar
Hypertonic

Question 3

what is hypovolaemic hyponatraemia due to

Answer 3

typically due to excess sodium loss

Question 4

how is SIADH related to hyponatraemia

Answer 4

persistent release of ADH leading to water retention

Question 5

what kind of hormonal insufficiency leads to hyponatraaemia

Answer 5

Addison’s
Hypothyroidism
Pregnancy – HCG ‘sets’ osmostat lower by 5 mmol/L

Question 6

why do we correct sodium level slowly

Answer 6

to avoid central pontine myelinolysis

Question 7

what are the common interventions for hyponatraemia

Answer 7

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

Question 8

when does nephrotic syndrome occur

Answer 8

when the basement membrane in the glomerulus becomes highly permeable to protein, allowing proteins to leak form the blood into the urine.

Question 9

in who is nephrotic syndrome most common

Answer 9

in children between the ages of 2 and 5

Question 10

how does nephrotic syndrome usually present

Answer 10

with frothy urine, generalised oedema, and pallor

Question 11

what is the classic triad of nephrotic syndrome

Answer 11

Low serum albumin
High urine protein content (>3+ protein on urine dipstick)
Oedema

Question 12

what are the three other features that occur in patients with nephrotic syndrome

Answer 12

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

Question 13

what are most cases of nephrotic syndrome due to

Answer 13

> 80% of cases are due to glomerulonephrotis

Question 14

what happens in this syndrome

Answer 14

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.

Question 15

what are the primary causes of nephrotic syndrome that are diagnoses of exclusion that are only made if secondary causes cannot be found

Answer 15

Minimal change disease (MCD)

Focal segmental glomerulosclerosis

Membranous nephropathy

Question 16

what are the secondary causes - note that these fall into the same three cateogries as the primary causes

Answer 16

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

Question 17

what does nephrotic syndrome increase the risks of

Answer 17

increased susceptibility to infection - partly due to loss of immunoglobulin in the urine

also increases the risk of thromboembolism and hyperlipidaemia

Question 18

what are the investigations for nephrotic syndrome

Answer 18

same carried out in glomerulonephritis

check cholesterol as part of confirming the presence of hyperlipidaemia

Question 19

why do you order a renal biopsy for adults

Answer 19

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

Question 20

what is the management of nephrotic syndrome usually based on

Answer 20

involves treatment of the underlying condition which is usually GN

therefore, fluid management and salt intake restriction are priorities

Question 21

what medications is the patient usually given in nephrotic syndrome

Answer 21

furosemide along with an ACE inhibitor and/or angiotensin II receptor antagonist

prophylatic heparin is given if the patient is immobile.

Question 22

what is hyperlipidaemia treated with

Answer 22

a statin

Question 23

describe the hypercoagulant state seen in nephrotic syndrome and how this presents and is treated

Answer 23

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

Question 24

what does diagnosis of PCOS require

Answer 24

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

Question 25

what is the first line medication approved for weight loss

Answer 25

ortlistat reduces the absorption of fat by inhibiting pancreatic and gastric lipases

Question 26

which drug is thought to suppress hunger

Answer 26

phentermine (duromine and metermine)

Question 27

what is obstructive sleep apnoea caused by

Answer 27

a collapse of the pharyngeal airway

Question 28

what is OSA characterised by

Answer 28

episodes of apnoea during sleep, where the person stops breathing periodically for up to a few minutes

Question 29

what are the risk factors for obstructive sleep apnoea

Answer 29

Middle age Male Obesity Alcohol Smoking

Question 30

what are the features of obstructive sleep apnoea

Answer 30

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

Question 31

what can severe episodes of obstructive sleep apnoea cause

Answer 31

Severe cases can cause hypertension, heart failure and can increase the risk of myocardial infarction and stroke.

Question 32

what is the Epworth Sleepiness Scale used to do

Answer 32

used to assess symptoms of sleepiness associated with obstructive sleep apnoea

Question 33

what is the top tip for OSCEs and OSA

Answer 33

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.

Question 34

what is the management of patients with obstructive sleep apnoea

Answer 34

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

Question 35

what is the first step of management in OSA

Answer 35

to correct reversible risk factors by advising them to stop drinking alcohol, smoking or lose weight

Question 36

what is the second step in management of OSA

Answer 36

to use CPAP machine that provides continuous pressure to maintain the patency of the airwau

Question 37

is surgery an option in obstructive sleep apnoea

Answer 37

yes. this involves quite significant surgical reconstruction of the soft palate and jaw. the most common procedure is a uvulopalatopharyngoplasty (UPPP).