Dr. Loh Keh Chuan, Consultant Endocrinologist at TTSH, spoke on "Primary Aldosteronism - Have We forgotten the Diagnosis?"  

Primary aldosteronism was first presented by Professor Conn in 1954 and over the years, there have been several revisions to the criteria for diagnosing Conn's Syndrome. The original criteria relied on the presence of hypokalemia, hypertension and hyperaldosteronism. Currently, patients are investigated for Conn's syndrome if they present with hypertension and hypokalemia.  

In Dr. Loh's institution, a serum potassium level less than 3.5 mmol/L is used as the threshold for confirmatory tests which involves assessing aldosterone suppressibility post salt-loading. Either urine aldosterone excretion is measured post oral salt-loading, or plasma aldosterone is measured post saline infusion.  

Dr. Loh shared the results of his study done on 350 hypertensive polyclinic patients in Singapore, aged between 25 to 75 years. These patients were screened for primary aldosteronism, using plasma aldosterone and plasma renin activity (PRA). He followed up with urine aldosterone measurements for those patients whose aldosterone to PRA (Aldo:PRA) ratio was above 20 and plasma aldosterone was above 15 ng/dL. Patients with urine aldosterone above 12 ug/day and plasma aldosterone above 10 ng/dL were considered positive for primary aldosteronism. Subtype study was done on confirmed cases using CT adrenal scan.  

One note of caution is that the cut-off limits indicated above are method-specific and should not be universally adopted.  

Dr. Loh concluded that hypokalemia is an insensitive marker for primary aldosteronism, resulting in underdiagnosis of the disease in Singapore. A case study was discussed to illustrate the approach towards the diagnosis of primary aldosteronism.  

Professor B. Halliwell, Head of the Dept. of Biochemistry, NUS spoke on "Free Radicals and Antioxidants - Room for the Clinical Biochemist". He reviewed the different types of free radicals and their effects in the human body including reactive oxygen species, superoxide radicals, hydrogen peroxide, "free" iron or copper and hydroxyl radicals, as well as enzymes capable of removing the free radicals such as superoxide dismutase.  

He presented a study on transgenic mice which showed that there must be a balance of antioxidants and oxidants for health, for example, unsaturated transferrin to mop up free plasma iron. Free radicals have been implicated in various conditions such as atherosclerosis, diabetes mellitus, cancer and ageing. However, their utility as prognostic markers for atherosclerosis later in life remains scientifically unproven.  

An interesting point that Prof. Halliwell brought up is that natural foods such as fresh fruits and vegetables rather than supplements such as Vitamin E and B-carotene help to reduce the risk of free radical damage in the body. The average Singaporean diet contains a more than adequate amount of antidoxidants. In his own laboratory, Prof. Halliwell was able to demonstrate that dark soy sauce had 10 times more trolox equivalent anti-oxidant capacities than red wine. For beverages, coffee had the least antioxidant capacity while green tea with milk had the highest. 

After the tea break, we had presentations from our ASEAN Federation of Endocrine Societies (AFES) Education Grant recipients, Mr Andrew Tee on 'Clinical Utility of Directly Measured LDL-Cholesterol' and Ms Ong Siew Kim on 'An Automated HPLC - New VariantTMII'. Both presentations attracted enthusiastic discussion from the floor, suggesting that there are still many unresolved issues in these areas.  

Thirteen posters were presented at the meeting. The Best Poster Prize was awarded to Ms Ong Siew Kim for her poster entitled 'A Comparative Study on Hba1c - VariantTM HPLC and DCA2000'. SACB thanks Dr Loh, Professor Halliwell and Dr William Chew for doing the honour as the judges. Abstracts of all these posters are included in this newsletter for the benefit of those who did not have a chance to view them.  

That evening, SACB members celebrated a highly antioxidant 9-course Chinese Banquet with black soy sauce fish, chicken and vegetables BUT there were no takers for green tea with milk!