[Purpose] The evaluation of iron metabolism in the treatment of renal anemia is recommended based on serum ferritin levels, which reflect the body’s stored iron, but no reference value for ferritin has been established to determine iron deficiency/excess. In this study, we examined the usefulness of the total body iron (TBI) estimation formula in healthy subjects proposed by Cable for hemodialysis patients. [Method] TBI is calculated as the sum of the two major compartments of iron in the body： hemoglobin iron and stored iron. First, TBI calculated on test day ① was set as the reference TBI, and then on test day ②, the estimated ferritin value calculated backward from hemoglobin using this reference TBI was compared with the actual measured ferritin value. In situations where iron metabolism forms a semi-closed system, TBI is constant and the estimated ferritin value agrees with the actual measured ferritin. However, the amount of iron in hemodialysis patients is not constant due to iron replacement and loss, so iron delivery is out of balance. This study examined the relationship between estimated ferritin and actual measured ferritin levels associated with fluctuating TBI in hemodialysis patients. [Results] In patients with diverse clinical backgrounds, estimated ferritin showed a universal relationship with measured ferritin depending on the rate of change in TBI. Thus, the TBI formula was considered a reasonable equation that can be extrapolated to hemodialysis patients. [Conclusion] TBI is expected as a novel surrogate marker of iron metabolism to evaluate iron deficiency, maldistribution, and excess based on absolute values of hemoglobin iron and stored iron, which are difficult to assess by serum ferritin levels.

A 68-year-old man with a 14-month history of dialysis was admitted to our hospital with a chief presentation of dysphagia. The next day, dyspnea developed, and the patient was intubated. On the fourth day of admission, tonic spasms and posterior arch retraction were observed. Tetanus was diagnosed, midazolam was administered, and as the spasms were uncontrollable, magnesium sulfate was administered repeatedly while checking the blood magnesium level, to achieve a target level of 2.5-3.0 mEq/L. Continuous infusion was not performed because of hemodialysis, and the seizures decreased as the blood concentration of magnesium increased. On the thirteenth day of hospitalization, bradycardia was observed, which increased the blood magnesium level to 2.9 mEq/L, and magnesium administration was discontinued. The patient weighed 70 kg and was given a total of 240 mEq12A intermittently, with an average increase in the blood concentration of 0.33 mEq/L per 20 mEq. Magnesium has recently been administered to treat tetanus； however, an appropriate dosage for patients undergoing dialysis remains unknown. In summary, we report a case in which magnesium sulfate was administered to a patient on hemodialysis who developed tetanus, and throughout treatment, his magnesium levels remained high.

This article is a correction of the contents stated in the Report of Committee of Renal Data Registry published in Volume 57, Issue 2, pp. 51-57 of this journal. [Adjustment of the 2022 value of dialysis prevalence] In the original report, the 2022 dialysis prevalence was calculated using an estimate of the general population. This prevalence has now been recalculated using the final 2022 general population value. As a result, the 2022 dialysis prevalence according to sex and age was found to be approximately 8.5％ lower for individuals aged＜30 years and 0.5-3.9％ higher for those aged ≥30 years compared with the values published in the report. However, this adjustment does not affect the interpretation or discussion. [Correction of dialysis incidence rate] The dialysis incidence rate for each calendar year should have been adjusted by the response rate. However, in the original report, this adjustment was overlooked. The rate has now been corrected and recalculated accordingly. Fortunately, these corrections do not affect the conclusions drawn in the paper.