Tuesday, December 26, 2006

ECG in MRCP(1)

ECG in MRCP(1)

Today I am going to give you a few examples of abnormal ECGs that are commonly asked in MRCP. However, remember a few basic facts first. Look at a normal ECG first!




1) Heart axis- if I and II are both ‘positive’, axis is normal.
2) If every P wave is followed by ORS, then it is sinus rhythm.
3) Normal PR interval is 0.12-0.20 sec.
4) Normal ORS width is less than 0.12s, if it is more than more than 0.12s, it suggests conduction defects.
5) QT interval- From QRS start to end of T wave. Usually QTc is used and it equals to QT interval divided by square root of RR interval. Normal value:0.35-0.43. ( I try to remember as 0.33-0.43, it is a popular question in MRCP Part 1 about causes of prolonged QT interval!)
6) ST segment: either elevation or depression implies infarction or ishaemia.

OK, today I am going to talk about abnormal heart axis. There are two types of abnormal axis either left axis deviation or right axis deviation.

1) Right axis deviation- You will know it if Lead I is negative.



Causes: All pathology causing right ventricular hypertrophy or strain such as cor pulmonale, pulmonary embolism.

2) Left axis deviation- You will notice this if Lead II and III are negative.



Causes: Left ventricular hypertrophy or strain. Such as hypertension, aortic stenosis.

Thursday, December 21, 2006

Merry Christmas and Happy New Year

Merry Christmas and Happy New Year




To all readers of this blog, I would like to express my heartfelt gratitude to all of you for being so supportive to this blog. I promise I will try to make this blog better and provide more useful MRCP tips to all of you!

" Merry Christmas " and " Happy New Year"

Make a wish now and hope you can pass your MRCP in 2007!!

Friday, December 01, 2006

Hyperparathyroidism in MRCP

Hyperparathyroidism in MRCP

OK, today we are going to discuss an important topic in endocrinology in MRCP, we are going to talk about hyperparathyroidism.

Hyperparathyroidism just means high levels of circulating parathyroid hormone. You must remember that there are three types of hyperparathyroidism, primary, secondary and tertiary.

1) Primary hyperparathyroidism
It is simple, there is no reason ( such as low Calcium level) for the raised parathyroid hormone. It is usually due to problems occurring to the parathyroid gland itself. Causes are adenoma, parathyroid hyperplasia or carcinoma.

2) Secondary hyperparathyroidism
Parathyroid gland is stimulated to secrete more parathyroid hormone due to some underlying reason such as low calcium because of renal failure, Vitamin D deficiency.

3) Tertiary hyperparathyroidism
After prolonged stimulation, the parathyroid gland becomes autonomous and secrets parathyroid hormone without any feedback mechanism

I hope to discuss more about primary hyperparathyroidism today because clinically, we see secondary and tertiary hyperparathyroidism mainly in renal failure patients.Therefore, they are not so important in your MRCP Part 1 and 2!

Presentation of Hyperparathyroidism

As you might still remember as a medical student, parathyroid hormone's main function is to mobilize calcium from bone ( therefore leading to hypercalcemia) and increase urinary phosphate excretion, therefore patients with primary hyperparathyroidism usually present with symptoms due to hypercalcemia.

Remember this old mnemonic:' bone,stones, abdominal groans and psychic moans'!
Other presentations include dehydration ( due to increased diuresis, the reason? Check your book now!), thirst, confusion and myopathy.

Clinical Signs

Not thing much to see and examine unless you get a patient with a very big adenoma or carcinoma. However, always look for associated endocrine neoplasia associated with hyperparathyroidism in MEN ( Multiple Endocrine Neoplasia) I and II such as hypertension ( due to phaeochromocytoma), features of acromegaly due to pituitary adenoma.

Investigations

Raised calcium with ALP
Urine calcium excretion is raised
Xray may show osteitis fibrosa cystica,pepper-pot skull and subperiosteal resorption

Plasma PTH- inapproriately raised! (of course!)

Treatment
Removal of the gland
Indications for operation ( American NIH consensus)
1) markedly elevated calcium (>3mmol)
2) impaired renal function
3) renal stones
4) nephrocalcinosis
5) reduced BMD
6) substantially elevated urinary calcium excretion (>10mmol/24h)

Tips for MRCP

1) remember to suspect MEN every time you diagnose primary hyperparathyroidism