Host:

After the human body ingests substances such as protein and fat, enzymes in the body break them down to gain energy. Once the enzymes involved in metabolizing substances experience abnormal changes, no energy can be generated. It will also cause the accumulation of substances such as organic acids and cause disease. Some babies will show symptoms such as fatigue, vomiting, and drowsiness, maybe it's due to a rare disease caused by this kind of abnormal organic acid metabolism.

Today, we've invited Hong Kong Children's Hospital, Paediatrics and Adolescent Medicine, Consultant, Dr Fung Cheuk-wing to explain it to us. Hello, Dr Fung. Can you share with us what is organic acidemia?

Dr Fung Cheuk-wing:

Actually, organic acidemia is an inherited metabolic disorder. Before explaining organic acidemias, we must first understand what is metabolism. Metabolism is actually how our body sustains life. This involves a series of biochemical reactions. For example, we eat a hamburger. It contains fat, protein and carbohydrates. After eating and digesting, how we absorb their energy depends on biochemical reactions. For example, for A to become B, there is an enzyme involved. If a gene defect causes enzyme deficiency, A cannot become B. A will accumulate in the body, even becomes harmful and toxic. And B is not enough, and not enough energy cause problems. Inherited metabolic disorders mean all the genetic defects that affect the biochemical reactions involved in metabolism.

Host:

The organic acidemia we're talking about is one of these metabolic diseases. What is it actually referring to? What enzyme is lacking?

Dr Fung Cheuk-wing:

Some amino acids cannot be broken down. Amino acids are some of the building blocks of protein. If it cannot be metabolized, the body will have no energy. This causes problems.

Host:

If the patient cannot break down protein, what are the symptoms?

Dr Fung Cheuk-wing:

It has a lot to do with energy, as everyone would have guessed. Under what conditions our body requires the most energy is the time when children get sick. For example, it may be some high-intensity activities or sleeping too much. I usually sleep for a dozen of hours without any problem, but these kids cannot stay hungry for too long. Or they have a serious illness or have big surgical operations. As said just now, they cannot break down too much protein. So, if they suddenly do not follow the diet and eat a steak, protein level is already exceeded. Then there will be problems.

Host:

How can parents find out?

Dr Fung Cheuk-wing:

Generally speaking, as mentioned before, A cannot become B. So, they don't have enough energy and get tired. They may have low blood sugar, feel weak all over or may sweat a lot. And then A is some toxin accumulation. For example, some organic acids, maybe lactic acid may accumulate.

Often, children's reactions are vomiting or loss of appetite. In severe cases, it can affect the brain, with possible epileptic seizure, or commonly known as cramps. Or they have unstable footsteps, even fall into a coma. The most serious case is death. Of course, other organs also need energy, for example the heart or kidneys. Those could all have problems.

Host:

These sound dangerous. What is the treatment like?

Dr Fung Cheuk-wing:

We can revisit the concept that A cannot become B. For example, if there is not enough B, maybe some vitamins, we can supplement them. Or A, we call it ammonia, when it is very high, we take it away with some medicine. In the long run, they can't eat too much protein. Diet therapy is the most important.

At Hong Kong Children's Hospital, we have a multidisciplinary medical team. There are doctors and specialist nurses. Most importantly, we have dietitians, they are the specialists who can help us calculate the suitable amount of protein for these children. Because they can't eat too much or too little, because it will hinder their growth. This break point is very difficult to calculate.

Host:

But does it mean there are many foods these children cannot eat? For example, rice, everyone knows rice has protein. Does it mean that they may not eat?

Dr Fung Cheuk-wing:

In fact, generally speaking, a five-year-old patient cannot eat more than 15 or 16 grams of protein each day. What does it actually mean? We all play mahjong. Actually, it's two pieces of meat the size of a mahjong tile. That's 14 grams. In fact, that's enough. Just now, you said it very well that because rice and porridge have their own protein so deduction is needed. For a five-year-old patient to achieve metabolic balance, in fact, eating a bowl of porridge in the morning, one bowl of rice in the afternoon or evening plus some vegetables, that's already exceeded the amount of protein they can have already. Their quality of life may become worse. They may not get to eat cake or cookies. Even some meat, they can't eat too much.

Host:

But have there been any breakthroughs in recent years?

Dr Fung Cheuk-wing:

Actually, yes. Hong Kong Children's Hospital is patient- and children-centered. So, during this time, we are working hard to introduce some new medical food. One of these is called low protein rice. This is good news because when these children eat some rice, if they're are not full, we can't give them more because there will be excessive protein. Many times, we need to add some oil to let them have enough energy and at the same time, feel full. Now there is this low-protein rice. There is no need to calculate the protein. It almost has no protein, so there's lots of room left to let the children taste meat, can even try some cake and cookies. I believe this is good news for patients.

Host:

Thank you doctor for sharing with us today. That's all for now. Goodbye.