Hemoglobinuria or myoglobinuria

Hemoglobinuria and myoglobinuria

I always confused these two conditions when I was a medical student. Now let me make these conditions as simple as possible.

Hemoglobinuria just means presence of hem in the urine whereas myoglobinuria means presence of myoglobin in the urine. Both can cause acute kidney injury due to pigment nephropathy.

Remember that both can cause a false positive in urine dipstick for RBC. Patients with both these conditions produce tea coloured urine. However myoglobinuria may be differentiated from hemoglobinuria by performing a series of simple tests.

-Myoglobinuria is brown, and often only a few RBCs are present in the urine.
-Hematuria produces a reddish sediment in spun urine samples.
-Red or brown urine with a negative dipstick result for blood indicates a dye in the urine.
-Hemoglobin produces a reddish or brown coloration in the spun serum, whereas myoglobin does not discolor the serum.
-CK levels are markedly elevated in myoglobinuria.

Another common question in MRCP- if you notice red to brown urine with negative dipstick, there are only a few possibilities- bladder analgesic phenazopyridine or a variety of other medications, certain food dyes, the ingestion of beets in susceptible subjects, porphyria and hydroxocobalamin for the treatment of cyanide intoxication.

Question in MRCP

A 17 year old male with glucose-6-phosphate dehydrogenase deficiency presents with tiredness and is noticed to
be jaundiced. These features have developed since he developed a mild chest infection one week ago. Which one
of the following is the most likely haematological finding?

1 ) Haemoglobinuria
2 ) low mean cell volume
3 ) Positive direct antiglobulin test
4 ) Reduced reticulocyte count
5 ) Spherocytes present on blood film

Answer: 1

Vasculitides in MRCP

Vasculitides in MRCP

Let me makes this topic a very simple one, you just to know two conditions in this topic- Wegener Granulomatosis and Chrug- Strauss Disease.

Anyway, before we zoom in into these two conditions, I think candidates need to know this topic as a whole, vasculitis just means inflammation of blood vessels with reactive damage to the wall which can lead to downstream ischemia and necrosis.

Classification of vasculitis is depending on the size of vessel involved. You might want to know more about Chapel Hill Classification- either big vessel, medium or small vessel.

However, I do not think you need to know all these conditions- for MRCP candidates- big vessels vasculitis, you need to know Giant cell arteritis, medium size vasculitis- you need to know polyarteritis nodosa and small vessel disease- of course you MUST know Wegener Granulomatosis (WG) and Churg-Strauss Disease ( CS)

I will talk about Giant cell arteritis and polyarteritis nodosa next time and for today, we will put emphasis on WG and CS.

( Wegener Granulomatosis patients usually go to see an ENT surgeon first!!)

Since both involve small vessels, multiple organs can be involved, however, just remember the following similarities and differences between these two conditions.

Both of WG and CS can cause pauci immune glomerulonephritis and the classical finding is cresentric GN on biopsy

Both can be ANCA positive but WG is mainly c-ANCA and CS is mainly p-ANCA
WG patients usually have upper respiratory airway problem and can be misdiagnosed as nasopharygeal carcinoma or tuberculosis.

For CS, patients might present with asthma and usually has eosinophilia.
Yes, you are right, that’s all you need to know!!

Please join NOW to help PassPACES to improve!

Tumour Lysis Syndrome in MRCP

Tumour Lysis Syndrome in MRCP

OK, this is a popular problem you see during your internship if you are working in an oncology ward. Remember that it is a MEDICAL EMERGENCY!

Tumor lysis syndrome (TLS) describes a condition with significant clinical and lab abnormalities caused by rapid and massive tumor cell death. Occurring either spontaneously or after chemotherapy. Therefore, it is quite logical to get this in patients with very high tumour load ( such as leukemia or lyphoma with very high white cell load)

You always encounter this syndrome post chemotherapy and always suspect this if patient develops acute kidney injury and hyperkalemia post chemotherapy.

Due to massive cell lysis, you will anticipate patients to have hyperkalemia, high phosphate and high uric acid with low Calcium.

Sometimes, patients might just present with seizure or cardiac arrthymias.

The pathogenesis of acute kidney injury is not so important for MRCP Part 1 and 2. Anyway you might get some ideas from the photo below,

About the amanegement, it is easy, the principles are below,

1) Adequately hydrate patient to prevent cystals formation

2) Prevent/minimize uric acid formation by giving allupurinol or rasburicase.

and of course sometime, you might need to dialyse the patient.