Normalization of haemoglobin improved QoL in the subgroup of dialysis patients, appears to be safe and can be considered in many patients with end-stage renal disease.

A simple metabolic investigation was carried out in 54 patients presenting with their first attack of renal stones. In three cases a probable cause for stone formation was found. During the following 8 years 53% of the patients developed recurrences, the risk of which was highest during the first years after the initial attack. Recurrences were more common in males than in females. As a group, patients who were to have recurrences had higher urinary calcium levels but there was a considerable overlap between the two groups. This prospective study confirms the opinion from retrospective evaluation of the natural history of renal stones that recurrences are common. However, they cannot be predicted from standard laboratory findings in individual patients.

The pharmacokinetics of a single intravenous injection of 100 mg iron hydroxide–sucrose complex labelled with a tracer in the form of 52Fe/59Fe was followed in six anaemic patients for a period ranging from 6 to 8.3 h using positron emission tomography (PET). Red cell utilization of the labelled iron was followed for 4 weeks. PET data showed radioactive uptake by the liver, spleen and bone marrow. The uptake by the macrophage‐rich spleen demonstrated the reticuloendothelial uptake of this iron preparation, with subsequent effective release of that iron for marrow utilization. Red cell utilization, followed for 4 weeks, ranged from 59% to 97%. The bone marrow influx rate constant was independent of blood iron concentration, indicating non‐saturation of the transport system in bone marrow. This implied that higher doses of the iron complex can probably be used in the same setting. A higher influx rate into the marrow compared with the liver seemed to be consistent with higher red cell utilization. This would indicate that early distribution of the injected iron complex may predict the long‐term utilization.

The magnesium status of 22 hemodialysis patients was studied by analyses of serum, skeletal muscle and peripheral blood lymphocyte levels of magnesium. Despite elevated serum magnesium, normal magnesium levels were noted in skeletal muscle and lymphocytes. 12 patients were exposed to a low dialysate magnesium concentration, resulting in normalization of serum magnesium but no changes in muscle or lymphocyte magnesium, which might indicate slow exchange between these intracellular stores and the extracellular fluid. Normalization of serum magnesium was followed by a slight rise in circulating parathyroid hormone levels without noticeable changes in serum calcium or phosphate levels. Since signs of an absolute magnesium excess were not detected, a combination of low dialysate magnesium and the use of an oral magnesium compound as a phosphate binder might be a way to decrease aluminium exposition in hemodialysis patients.

Summary. Parenteral iron–polysaccharide complexes are increasingly applied. The pharmacokinetics of iron sucrose have been assessed by our group using positron emission tomography (PET). A single intravenous injection of 100 mg iron as iron (III) hydroxide–polymaltose complex, labelled with a tracer in the form of 52Fe/59Fe, was similarly assessed in six patients using PET for about 8 h. Red cell utilization was followed for 4 weeks. Iron polymaltose was similarly distributed to the liver, spleen and bone marrow. However, a larger proportion of this complex was rapidly distributed to the bone marrow. The shorter equilibration phase for the liver, about 25 min, indicates the minimal role of the liver for direct distribution. Splenic uptake also reflected the reticuloendothelial handling of this complex. Red cell utilization ranged from 61% to 99%. Despite the relatively higher uptake by the bone marrow, there was no saturation of marrow transport systems at this dose level. In conclusion, high red cell utilization of iron polymaltose occurred in anaemic patients. The major portion of the injected dose was rapidly distributed to the bone marrow. In addition, the reticuloendothelial uptake of this complex may reflect the safety of polysaccharide complexes. Non‐saturation of transport systems to the bone marrow indicated the presence of a large interstitial transport pool, which might possibly be transferrin.