Hyponatraemia is frequent in older people and induces marked motor and cognitive dysfunction, even in patients deemed 'asymptomatic'. Nutritional status is worse than in euvolaemic-matched controls, and the risk of fracture is increased following incidental falls. Yet hyponatraemia is undertreated, in spite of the fact that its correction is accompanied by a clear improvement in symptoms. Both evaluation of neurological symptoms and classification by volaemia are essential for a correct diagnosis and treatment of the hyponatraemic elderly patient. The syndrome of inappropriate anti-diuretic hormone secretion (SIADH) is the most common cause of hyponatraemia in older people. Nutritional status and chronicity of SIADH should be taken into account when deciding therapy. We propose an 8-step approach to the management of the elderly patient with hyponatraemia.

In women with osteoarthritis of the knee treated with a meal-replacement diet, there is a significant decrease in weight and fat mass with a relative increase of the latter. There is an improvement in the quality of life according to SF-36 and WOMAC. There is an independent relationship between weight loss and SF-36 improvement.

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In Spain, certain population-based studies have shown high blood mercury (Hg) levels due to the high consumption of fish. Some studies have stated that one of the most consumed fish in Spain is canned tuna. Different Spanish organisms consider that it is safe to consume canned tuna as it supposedly has a low mercury content, particularly in so-called light tuna. However, in Spain light tuna is mainly yellowfin and bigeye tuna, while in other countries it is mainly skipjack tuna. This study analyzed 36 cans of the most popular brands in Spain and examined the influence of the type of tuna, packaging medium (olive oil, sunflower seed oil, water or marinade), different brands, prices and expiration dates. Mercury concentrations (mg/kg) were measured by atomic absorption spectrometry and thermal decomposition amalgamation. The medians observed were (mg/kg): light tuna: 0.314; IQR: 0.205 - 0.594, white tuna: 0.338; IQR: 0.276 - 0.558, skipjack: 0.311; IQR: 0.299 - 0.322, frigate tuna: 0.219; IQR 0.182 - 0.257 and mackerel: 0.042; IQR 0.029 - 0.074. We found statistically significant differences between white tuna, light tuna and mackerel (p = 0.004); light tuna and mackerel (p = 0.002) and white tuna and mackerel (p = 0.006). However, we found no differences between white tuna and light tuna, or among packaging medium, brands, prices or expiration dates. The limit of 0.500 mg/kg of mercury in canned tuna was exceeded by the following percentages of the cans: 33.3% of light tuna, 16.7% of white tuna, and 0% of Skipjack, frigate tuna and mackerel. The mercury content of the cans of Spanish light tuna that were analyzed was variable and high. The results of this study indicate that stricter regulation of Hg in canned tuna is necessary. Until then, it is safer to recommend that vulnerable populations such as children and pregnant women consume canned mackerel, which has a markedly lower mercury content.