MedMCQ-Medical MCQs,Qbank

A 34-year-old woman presents to accident and emergency complaining of severe abdominal pain associated with weakness of both legs. She states that the symptoms started in the morning and have steadily gotten worse. She complains of abdominal pain that is generalised but much worse in the suprapubic region but denies any dysuria. A sample of urine for dipstick was dark in colour but was negative for blood, protein or nitrites on testing. On examination the abdomen is soft but tender over the suprapubic region and neurological examination reveals markedly reduced sensation in the distal lower limbs but normal tone, power and co-ordination. You notice that during the examination she has been frantically looking through her observations and drug charts and stating that no documentation must be taken as the government have been spying on her. Which of the following investigations would be most useful in making the diagnosis?

• A. 24-hour urinary protein collection
• B. Thyroid function tests
• C. Urinary porphobilinogen levels
• D. CT scan of the abdomen
• E. Urinary metanephrines (HMMA/VMA)

Correct Answer:C

The presentation of abdominal pain, new-onset neuropsychiatric symptoms in a young woman should always alert the clinician to the possibility of acute intermittent porphyria (AIP) as the diagnosis. The porphyrias are a set of genetic disorders of haem biosynthesis resulting in increased levels of porphyrin precursors such as porphobilinogen and 5-δ-aminolaevulinic acid. Skin involvement is a feature of some varieties of porphyria and may be the presenting feature. Other clinical features can be summed up by ‘the four H’s, P’s and S’s’:

• Hypotonia, Hypotension, Hyponatraemia, Hypokalaemia
• Proteinuria, Psychosis, Paralysis, Peripheral neuritis
• Seizures, Shock, Sensory impairment, viSual abnormalities

The urine may appear dark or deep red especially on standing and testing for urinary porphobilinogen and 5-δ-aminolaevulinic acid levels aids in diagnosis. Thyroid function tests may be helpful in patients with features of thyroid dysfunction and confusion or psychiatric symptoms; however, the clinical picture is not typical for thyroid dysfunction. Phaeochromocytoma may cause symptoms of anxiety, depression and a sense of impending doom. Levels of adrenaline metabolites can be assayed in a 24-hour urine collection; however, a phaeochromocytoma crisis manifests with sympathetic overactivity, which can help to differentiate organic from functional causes of psychosis. CT scan of the abdomen is a reasonable line of investigation to proceed with once simple causes of abdominal pain and psychiatric disturbance have been ruled out as malignancy and especially hormonesecreting tumours may cause the above picture.