General practice is in an ideal position to identify hazardous drinking. However, a high level of suspicion may be required to detect alcohol-related issues as they can be easily missed or “disguised” by other health problems. It is currently recommended that a useful approach for detecting hazardous drinking is to integrate two to three simple questions about alcohol use into a primary care consultation to provide an opening for a more in-depth discussion.

Laboratory tests are not recommended for the routine screening of hazardous drinking in primary care. This is because, although blood tests frequently show a number of changes in relation to alcohol use, they generally lack sufficient sensitivity and specificity for this purpose. Instead, studies have shown that validated questionnaires are the best way to screen for hazardous alcohol use because they are more sensitive, more specific and less expensive than blood tests, which are only indicated as an adjunct to screening.

Alcohol consumption is an established part of New Zealand culture, with 80% of all adults over the age of 18 years, identifying themselves as current drinkers.

It has been estimated that 20–25% of New Zealanders consume alcohol at a harmful or hazardous level. It is important to keep in mind that the harms associated with alcohol are not just confined to the heaviest drinkers. Research has identified that the majority of alcohol related problems in people who drink are seen in the 90% that consume alcohol moderately, compared to the 10% that drink heavily.

Fish is by far the biggest source of exposure to organic mercury, in the form of methyl mercury. Organic mercury is passed along the food chain from smaller fish to larger predator fish, e.g. swordfish, shark, tuna, which contain the highest levels of accumulated mercury. Inhalation and skin absorption of mercury can occur when handling liquid mercury, e.g. broken thermometers, sphygmomanometers, fluorescent light bulbs. Dental amalgam fillings contain mercury but contribute only a minor amount to the total mercury levels in the body.

Situations in which mercury testing is indicated include; history of mercury ingestion (other than normal consumption of fish), known occupational risk or neurological symptoms that may be the result of mercury poisoning.
Situations in which mercury testing is not indicated include; patients with non-specific symptoms such as memory loss, cognitive decline, depression or chronic fatigue syndrome, the presence of amalgam fillings, autism spectrum disorder or Alzheimer’s disease (there is no convincing evidence that mercury is linked to either of these conditions) or routine “screening” or an “annual check”.

Although the INR target range is usually 2.0 – 3.0, in most cases it is only in this range approximately 55 to 60% of the time. Computerised decision support provides an automated system in which the time within target can be increased to up to 70% in some cases.

Regular testing of the INR is essential for all people taking warfarin. For most people once the INR is stable, the rate of INR testing can be extended to two weekly and then four to six weekly. In some stable patients the frequency may be extended out to eight weeks. However, people with higher levels of risk, e.g. certain co-morbidities, may need more frequent testing.

Examples of some co-morbidities which can influence INR results:

• Congestive heart failure – may cause hepatic congestion of blood flow and inhibit warfarin metabolism, this may be particularly troublesome during exacerbations of heart failure
• Hypothyroidism – decreased catabolism of vitamin K clotting factors may decrease INR values
• Hyperthyroidism – conversely, hyperthyroidism may increase catabolism of vitamin K clotting factors and increase INR values
• Liver failure – may cause elevation of INR due to reduced production of clotting factors
• Other illnesses – other intermittent conditions such as fever, vomiting and diarrhoea may affect the INR; ill patients may also reduce their usual dietary intake