MedGems Chempath

Question 1

What condition describes inadequate function of the proximal renal tubules of the kidney and is associated with glucosuria, hypophosphatemia and hyperuricosuria?

Answer 1

Fanconi Syndrome

Question 2

A 9 year old boy presents to the GP with enlarged orange coloured tonsils.

Examination elicits a peripheral neuropathy and blood tests show very low plasma HDL levels.

What is the most likely diagnosis?

Answer 2

Tangier disease

Question 3

In the liver which cytochrome P450 enzyme catalyses the first step in the formation of bile acids via the classical pathway?

Answer 3

Cholesterol 7 alpha hydroxylase

Question 4

A 14 month old boy presents showing signs of delayed motor development and self-mutilation of the lips and fingers. He is found to have hyperuricaemia.

What enzyme is deficient in this condition?

Answer 4

Lesch Nyhan syndrome - HGPRT enzyme is deficient

Question 5

A patient with Bipolar Affective Disorder complains of excessive thirst and says they have been drinking more than usual and passing urine more frequently for some time now.

Urine osmolality is low. Blood glucose is 5.1 mmol/L.

You decide to do a water deprivation test.

At the start of the test urine osmolality is 196 mOsmol/kg and after 4 hours urine osmolality remains low.

After a subcutaneous injection of Desmopressin is given urine osmolality is 204 mOsmol/kg.

What is the most likely underlying diagnosis?

Answer 5

Arginine vasopressin resistance

Question 6

A 3 year old child is seen in the paediatric clinic after concerns about failure to thrive.

He has already been diagnosed with rickets and is on appropriate calcium and vitamin D replacement.

Blood tests show him to be hypokalaemic.

Urine dip shows the presence of protein and glucose. The pH of the urine is 8.6 (alkaline). There are no ketones in his blood.

What is the probable explanation for his failure to thrive, blood test result and urine dip findings?

Answer 6

Fanconi syndrome

Question 7

Where in the nephron is the majority of bicarbonate reabsorbed?

Answer 7

Proximal convoluted tubule

Question 8

Their ECG shows a very broad complex tachycardia. The team are unable to record a blood pressure. The medical student comments the ECG trace “almost looks like a sine wave”.

Electrolyte abnormality?

Answer 8

Hyperkalaemia

Question 9

A patient’s blood tests have returned and show they have a low serum sodium level. What investigation should be done to determine if this is a true hyponatraemia?

Answer 9

serum osmolality

Question 10

A urine dipstick positive for blood but negative for erythrocytes on direct microscopy suggests the presence of what molecule?

Answer 10

Myoglobin
Rhabdomyolysis describes necrosis of muscle and release of intracellular components. It may be caused by traumatic crush injuries. A serum creatine kinase measurement greater than 5 times the upper limit of normal is considered diagnostic. Myoglobin is a protein normally present in urine in small amounts. The muscle breakdown in rhabdomyolysis causes raised serum myoglobin which leads to myoglobinuria. The high levels of myoglobin in the urine are responsible for the dark brown colour. It may occur after vigorous exercise. A urine dipstick test measures the peroxidase activity of erythrocytes and therefore will be positive for blood if myoglobin is present.

Question 11

In which organ does the enzyme 25 hydroxylase convert cholecalciferol to 25-hydroxycholecalciferol?

Answer 11

Liver

Question 12

What family of enzymes in the gut does Orlistat inhibit?

Answer 12

Lipases

Question 13

In uric acid metabolism, what does FEUA stand for?

Answer 13

fractional extretion of uric acid

Question 14

ApoE4 classically gives an increased risk of developing which neurodegenerative condition?

Answer 14

Alzheimer’s disease

Question 15

Where in the gut are bile acids reabsorbed?

Answer 15

Terminal ileum

Question 16

A young man is brought to the emergency department confused. He is mumbling nonsensical phrases and hyperventilating. The paramedics state he was found next to a number of white, circular pills however they were unable to determine what these were.

A panel of bloods reveals normal kidney function, but a low bicarbonate (17, NR 22-28) .

A head CT was unremarkable. Urine Drug Screen negative. Blood Alcohol levels negative.

An ABG reveals a pH of 7.5 (NR 7.35-7.45)

What drug is the patient likely to have overdosed on?

Answer 16

Salicylates

Question 17

What class of drug must not be co-administered with azathioprine in individuals with TPMT deficiency, else a potentially fatal buildup of toxic metabolites may occur?

Answer 17

Xanthine oxidase inhibitors

Question 18

Which enzyme forms the rate limiting step in de novo purine synthesis?

Answer 18

PAT
Phosphoribosyl pyrophosphate amidotransferase (PAT)

Question 19

A 24 year old lady is referred to a cardiologist.

She has irregular yellow growths on her hands and one on her achilles tendon.

The cardiologist informs her she has premature atherosclerosis.

Blood tests show grossly raised levels of plant sterol in her blood.

Which autosomal recessive disorder does she most likely have?

Answer 19

Phytosterolaemia

Question 20

A 36 year old man with Wilson’s disease is noted to be hypokalaemic on routine bloods performed at his GP.

He denies any nausea, vomiting or diarrhoea. His oral intake is normal for him and he doesn’t feel he is losing weight. He does not drink any alcohol. He is on no regular medications.

A urine dip is normal.

What condition is associated with Wilson’s disease which may cause hypokalaemia?

Answer 20

Renal tubular Acidosis

Question 21

What score, derived from a DEXA scan, describes how a patient’s bone mass varies compared to an age matched control?

Answer 21

Z-score

Question 22

Under polarised light, what colour would you expect needle shaped crystals to appear when parallel to a red filter?

Answer 22

Orange

Question 23

Under polarised light, what colour would you expect needle shaped crystals to appear when perpendicular to a red filter?

Answer 23

blue

Question 24

A patient with chronic kidney disease (CKD) has low calcium and raised phosphate. PTH levels are found to be high. What kind of hyperparathyroidism does this patient have?

Answer 24

Secondary

Question 25

In familial hypocalciuric hypercalcaemia (FHH), which receptor has suffered a mutation?

Answer 25

Calcium Sensing Receptor

Question 26

What vitamin converts cyanide to a renally cleared, less toxic, metabolite and is the first line medication for cyanide poisoning?

Answer 26

Hydroxocobalamin

Question 27

Give an example of a raised anion gap metabolic acidosis

Answer 27

GOLDMARK

Question 28

An alcoholic is admitted for treatment of alcohol withdrawal. He is started on chlordiazepoxide and vitamin supplementation. The patient is found to have a low serum sodium and so the F1 starts him on IV fluids and his serum sodium rises rapidly. Over the next few days he becomes progressively lethargic, has trouble speaking, swallowing and walking.

What is the most likely diagnosis?

Answer 28

Central pontine myelinolysis

Question 29

Purines can be made via a de novo synthesis pathway.

What is the name of the other pathway by which purines can be made?

Answer 29

Salvage pathway

Question 30

What is the inheritance pattern of Gilbert’s syndrome?

Answer 30

Autosomal recessive

Question 31

Phytosterolemia (Sitosterolemia) is a disorder characterised by raised levels of plant sterol in the blood.

Name a gene which undergoes a mutation causing this disorder?

Answer 31

ABCG5

Question 32

You are handed the following VBG while working in the emergency department.

The patient has type 1 diabetes and is very unwell, with a recorded fever of 38C and a blood pressure of 98/46

pH 7.20
BE -12
Na 140mmol/L
K 4mmol/L
Cl 100mmol/L
HCO3 15mmol/L
Glucose 12mmol/L
Lactate 12mmol/L

You are also given the urea (13mmol/L) and serum osmolarity which is 320mmol/L

What is the anion responsible for the patient’s metabolic acidosis?

Answer 32

Lactate

Question 33

Normal anion gap

Answer 33

14-18

Question 34

What does Cholestyramine bind to in the gut in order to cause the liver to break down more cholesterol?

Answer 34

Bile acids

Question 35

What kind of inheritance is shown by the Multiple Endocrine Neoplasia syndromes?

Answer 35

Autosomal dominant

Question 36

What enzyme is deficient or absent in acute intermittent porphyria?

Answer 36

HMB - hydroxymethylbilane synthase

Question 37

What is the inheritance pattern of acute intermittent porphyria?

Answer 37

Autosomal dominant

Question 38

What drug can be offered as a treatment during a flare of acute porphyrias?

Answer 38

Haem arginate

Question 39

A 23 year old woman is reviewed in the outpatient neurology clinic. She has a past medical history of epilepsy for which she takes levetiracetam.

Due to ongoing seizures, her neurologist asked her to produce a seizure diary which suggested that her seizures are often triggered by alcohol consumption, although she states that her overall alcohol consumption is low at less than 10 units a week.

On further questioning, she has also been given a diagnosis of IBS by a specialist and that her symptoms seem to flare shortly before she develops seizures.

What first line test would be highly suggestive of the underlying condition for all of her symptoms?

Answer 39

Urine porphobilinogen

Question 40

A 6 month old infant is taken on holiday by its parents to the South of France in Summer.

Whilst there, the infant develops severe blisters over sun exposed sites. In hospital, there is evidence of a haemolytic anaemia.

A urine test is positive for haem precursor proteins.

What is the likely diagnosis?

Answer 40

Congenital Erythropoietic prophyria

Question 41

What is the most common type of porphyria in the UK?

Answer 41

Porphyria cutanea tarda

Question 42

What is the most common acute porphyria in the UK?

Answer 42

Acute Intermittent Porphyria