Reference distributions for serum iron and transferrin saturation: a comparison of a large cohort to the world's literature

The appropriate clinical use of serum iron and transferrin saturation (TSAT) requires satisfactory reference intervals from birth to old age, and for males and females. This study identified 54 publications from 1974 to 2001 that met the criteria used in three prior meta-analyses, and these were analyzed statistically. A summary of our review is presented along with our reference population data on these measurements. This analysis places previous publications in perspective and suggests possible reasons for the observed differences. Previous studies of the individual analytes, serum iron, transferrin, and TSAT values agree with the reference ranges presented in this study, although the entire experience over time and between sexes has not been available before. Our 95% reference ranges are somewhat broader than those of the smaller studies, but they agree well with those of the larger ones.     

Reference distributions for the negative acute-phase serum proteins, albumin, transferrin and transthyretin: a practical, simple and clinically relevant approach in a large cohort

Inflammation is associated with diverse clinical conditions accompanied by characteristic changes in serum levels of the acute-phase proteins that can be used to stage the inflammatory process and evaluate the impact of treatment. Some acute-phase proteins increase during inflammation, while others, such as albumin, transferrin, and transthyretin, decrease. The current study reports reference ranges for serum levels of albumin, transferrin, and transthyretin based on a cohort of over 124,000 Caucasian individuals from northern New England, tested in our laboratory between 1986 and 1998. Measurements were standardized against CRM 470 (RPPHS) and analyzed using a previously validated statistical approach. Individuals with laboratory evidence of inflammation (C-reactive protein of 10 mg/L or higher) were excluded. The levels of all three analytes varied by age, generally rising until the second or third decade of life and then decreasing thereafter. Albumin and transthyretin levels were higher during midlife among males as compared to females; the maximum being at 25 years for albumin (5%) and 35 years for transthyretin (16%). In contrast, above the age of 10 years, transferrin levels were increasingly higher among females (7% at 20 years). When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution. When patient data are normalized in this manner, the distribution parameters can be used to assign a corresponding centile to an individual's measurement simplifying interpretation. The ultimate interpretation of an individual's measurement relies upon the clinical setting.     

Daily doses of 20 mg of elemental iron compensate for iron loss in regular blood donors: a randomized, double-blind, placebo-controlled study

BACKGROUND: A considerable number of regular blood donors develops an iron deficiency, and the exact amount of iron required to compensate for the iron loss from whole-blood donation in males and females is still unknown. STUDY DESIGN AND METHODS: A total of 526 regular blood donors (289 male and 237 female) were randomly assigned to treatment with either 40 mg, 20 mg, or 0 mg per day of elemental iron as ferrous gluconate for a period of 6 months, during which one unit of whole blood was collected on four occasions (males) or three occasions (females). Hemoglobin level, serum ferritin, and soluble transferrin receptor levels were measured before each donation. RESULTS: Daily doses of either 40 mg or 20 mg of elemental iron adequately compensated for iron loss in males, who gave blood at 2-month intervals, but did not result in a positive iron balance or an increase in storage iron as reflected by the logarithm of the ratio of transferrin receptor to ferritin concentration. In females, who donated at 3-month intervals, the same daily doses not only restored the iron balance but also led to an increase in storage iron. The number of gastrointestinal side effects due to iron supplementation (12%) was only slightly higher in both iron groups than in the placebo group. CONCLUSION: The results of this study indicate that 20 mg of elemental iron per day can adequately compensate for iron loss in males and females who donate whole blood up to four (females) or six times per year (males).     

静脉与口服维生素C对维持性血液透析患者铁超负荷的疗效观察

目的观察静脉与口服维生素C（VitC）治疗维持性血液透析（MHD）铁超负荷患者疗效。方法选择中南大学湘雅二医院肾内科行血液透析患者血清铁蛋白（SF）〉800ng／ml和（或）转铁蛋白饱和度（TSAT）〉50％30例，随机分为3组，对照组（n=10）、口服组（n=10）和静脉组（n=10）。观察用药前后SF、TSAT、血红蛋白（Hb）、红细胞压积（Hct）和血浆丙二醛（MDA）的变化。结果治疗12周后，静脉组SF、TSAT降低，Hb、Hct升高，与对照组、口服组差异有显著性（P〈0．01）；口服组SF、TSAT、Hb、Hct稍有改善，与对照组比较无统计学意义（P〉0．05）而PMDA、PSOD无统计学意义。结论MHD铁超负荷患者静脉滴注VitC优于口服。     

Reference distributions for alpha2-macroglobulin: a practical, simple and clinically relevant approach in a large cohort

In this 11th article in a series, reference values of serum levels alpha(2)-macroglobulin alpha(2)M) are examined. The study is based on a cohort of 40,420 Caucasian individuals from northern New England that were tested in our laboratory between 1994 and 2000. Measurements were standardized against Certified Reference Material (CRM 470)/Reference Preparation for Proteins in Human Serum (RPPHS) and the results analyzed using a previously described statistical approach. Individuals with unequivocal laboratory evidence of inflammation (C-reactive protein >10 mg/L) were excluded in one leg of the study and included in the other, confirming that alpha(2)M does not respond to acute phase drive in man. Nephrotic syndrome, diabetes mellitus, and chronic liver disease have significant effect on levels of alpha(2)M. Dramatic changes occur during life with males higher from birth to age 12, females thereafter have higher values until the ninth decade. When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution well over a broad range. When patient data are normalized in this manner, the distribution parameters can be used to assign a centile corresponding to an individual's measurement thus simplifying interpretation.     

Reference distributions for complement proteins C3 and C4: a practical, simple and clinically relevant approach in a large cohort

The two serum proteins of the complement cascade in the highest concentrations, C3 and C4, respond to various conditions in much the same manner as do other positive acute-phase proteins. A major difference is that they are relatively sluggish in response to cytokine drive, requiring several days rather than hours to be detectably elevated by serial measurements. As with other acute-phase proteins, there are many processes that up- or down-regulate synthesis, including infection or inflammation, hepatic failure, and immune-complex formation. Clinicians may find it difficult to distinguish among these processes, because they often occur simultaneously. The situation is further complicated by genetic polymorphism, with rare instances of markedly reduced synthesis and circulating levels, and consequent vulnerability to infection. C3 and C4 are measured for clinical purposes to help define certain rheumatic and immunologically mediated renal diseases. Interpreting the measured blood levels of these two components requires one to consider the intensity of the inflammatory drive, the timing of the suspected clinical process, the production of complement-consuming immune complexes, and the possible existence of benign circumstances. In this fifth article in a series, reference ranges for serum levels of two complement proteins (C3 and C4) are examined. The study is based on a cohort of over 55,000 Caucasian individuals from northern New England, who were tested in our laboratory in 1994-1999. Measurements were standardized against certified reference material (CRM) 470/reference preparation for proteins in human serum (RPPHS), and analyzed using a previously described statistical approach. Individuals with unequivocal laboratory evidence of inflammation (C-reactive protein of 10 mg/L or higher) were excluded. Our results show that the levels of C3 and C4 change little during life and between the sexes, except that they increase slightly and then fall after age 20 in males and at about age 45 in females. When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution well over a broad range. When patient data are normalized in this manner, the distribution parameters can be used to assign a centile corresponding to an individual's measurement, thus simplifying interpretation.     

Effect of hemochromatosis genotype and lifestyle factors on iron and red cell indices in a community population

BACKGROUND: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects. METHODS: We performed a cross-sectional analysis of 1488 females and 1522 males 20-79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices. RESULTS: Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20-29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 microg/L; P = 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1-2 times per week and alcohol intakes >10 g/day. CONCLUSIONS: Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype.     

西藏不同海拔地区人群红细胞代谢相关血清学指标分析

目的 探讨西藏不同海拔地区藏族人群红细胞代谢相关血清学指标特征,并建立各指标的参考区间.方法 2016年9月—2018年8月,采用整群抽样法随机抽取西藏阿里地区(海拔Ⅰ,海拔4298～4352 m)、拉萨市和日喀则市(海拔Ⅱ,海拔3670～3835 m)、林芝市(海拔Ⅲ,海拔约2900 m)常住人群为研究对象.采集其血...     

某地区健康成人血清总蛋白、清蛋白以及白/球蛋白比值的参考值范围调查

目的 建立某地区健康成人血清总蛋白(TP)、清蛋白(ALB)以及白/球蛋白比值(A/G)的参考值范围.方法 采用Dimension RxL MAX全自动生化分析仪检测某地区3 413例健康成人血清TP、ALB,根据公式计算A/G,统计各自的参考值范围.结果 某地区健康成人TP与性别无明显相关性,>18～≤20岁年龄段的TP、ALB均高于其他年龄段(P<0.01),男性ALB于各个年龄段均明显高于女性(P<0.05).随着年龄的增长,男、女TP、ALB均呈下降趋势,但差异并无统计学意义.某地区健康成人总体参考值范围分别为:TP 66.82～81.76 g/L,ALB 39.69～49.81 g/L,A/G 1.16～1.98.结论 随着人们生活水平的不断提高及一些新的检验仪器以及新的检验方法的应用,实验室不应沿用旧的血清TP、ALB及A/G参考值范围,应建立某地区甚至本方法的正常参考值范围,才能满足临床诊断需求.     

Reference distributions for immunoglobulins A,G, and M: A practical,simple, and clinically relevant approach in a large cohort

Serum immunoglobulins are measured millions of times each year, yet clinical interpretations remain hampered by inadequate age- and gender-specific reference limits. In order to provide more reliable and comprehensive reference distributions for IgA, IgG, and IgM measurements, we analyzed automated immunoassay values from 115,017 serum samples from northern New England patients (99% Caucasian) who were tested in our laboratory between 1986 and 1995. Measurements were standardized to reference material, CRM 470 (RPPHS). A simple, practical, and clinically relevant approach was used to determine reference distributions for the immunoglobulins over a wide range of ages for males and females. Levels of IgA and IgM varied considerably by age, and by gender for IgM. For each of the analytes, the observed 5th and 95th centiles were symmetric about the median and approximately constant over the entire age range. When immunoglobulin reference values are expressed as multiples of the age- and gender-specific regressed medians, the resulting distributions fit a log-Gaussian distribution well. This finding enables interpretation of serum immunoglobulin measurements using a common unit (multiples of the median) that is independent of age or gender. Insights gained from this study can help improve and simplify the interpretation of immunoglobulin measurements. J. Clin. Lab. Anal. 12:363–370, 1998. © 1998 Wiley-Liss, Inc.     

Serum ferritin, blood donation, iron stores and haemochromatosis

Summary. Serum iron and ferritin concentrations were measured in 1,532 regular blood donors from South Wales who were undergoing HLA typing prior to registration on the British Bone Marrow and Platelet Donor Panel. Serum transferrin concentrations were determined for donors with serum iron concentrations > 24 µmol/1. There were 25 donors with transferrin saturations > 50% and 11 with transferrin saturations > 60%. There were five donors with serum ferritin concentrations > 200 µg/1 (women) or > 300 µg/1 (men). Two of the male donors had transferrin saturations > 50% and serum ferritin >300 µg/1 on repeat blood samples and are being treated by venesection. Donors with HLA-A3 did not differ from those without A3 in serum iron or ferritin concentrations. Even in the group of donors who were apparently homozygous for A3 there were neither abnormal serum iron nor ferritin concentrations.
Although it is well established that measurements of transferrin saturation are required to detect homozygous haemochromatosis ( HFE ) in its earlier stages, the number of 'false-positive' results is likely to be unacceptably high for screening blood donors. Serum ferritin assays should identify donors with HFE and iron overload before the onset of liver damage. With two million regular donors and 300,000 new donors each year, a significant proportion of the U.K. population will be screened within 10 years. The assay of serum ferritin identifies donors with low levels of storage iron who are at risk of developing iron-deficiency anaemia. Furthermore, donation frequency may be increased for those donors with higher ferritin concentrations when blood supplies are low.     

Haematological laboratory findings in the elderly: influence of age and sex

The effects of age and sex on haematological laboratory parameters were studied in connection with a population study in people over the age of 65 years (n = 347). Serum vitamin B12 was the only parameter which decreased significantly with advancing age. Blood leucocyte count, haemoglobin concentration, haematocrit, erythrocyte count, mean erythrocyte volume, mean erythrocyte haemoglobin and serum ferritin values were significantly higher in males than in females. Serum iron, serum transferrin, and plasma and erythrocyte folate levels did not differ between males and females. Thirteen subjects were anaemic and three of them had iron deficiency anaemia. Five subjects had iron deficiency based on serum iron and transferrin but no anaemia. Serum ferritin measurement did not reveal any further subjects with iron deficiency. No case of folate deficiency anaemia was revealed. Although many of the participants were on medication, most of them were living at home and taking care of themselves and represent relatively fit elderly people. Therefore we suggest that these laboratory data can also serve as reference values for the elderly people.     

静脉用右旋糖酐氢氧化铁注射液治疗腹膜透析患者肾性贫血的临床研究

目的评价右旋糖酐氢氧化铁注射液治疗腹膜透析患者铁缺乏的有效性及安全性。方法选择第二军医大学附属长海医院肾内科59例长期不卧床腹膜透析(CAPD)患者,肾性贫血程度:血红蛋白(Hb)60～90g/L,或红细胞压积(Hct)0.18%～0.27%,随机分为静脉组与口服组,分别采用静脉注射右旋糖酐氢氧化铁及口服琥珀酸亚铁进行补铁治疗,总疗程8周。检测治疗前治疗后8周时血清铁指标、红细胞相关指标及生化指标,并对不良反应进行监测。结果①共50例完成本临床研究,其中静脉组与口服组各25例,两组患者年龄、性别、贫血程度、血清铁指标及促红细胞生成素(EPO)用量相匹配。②治疗8周时,静脉组Hb及Hct显著升高,分别为(24.1±17.9)%和(27.2±19.7)%,幅度明显高于口服组[(12.1±16.5)%和(15.8±11.8)%],P<0.001。③治疗8周时,两组血清铁蛋白(SF)与转铁蛋白饱和度(TSAT)均较治疗前显著升高,且静脉组升高幅度[SF(487.3±390.8)%,TSAT(93.1±87.0)%]明显高于口服组[SF(178.9±271.7)%,TSAT(38.9±41.7)%],P<0.001。④治疗8周时,静脉组血清白蛋白及血清钾较治疗前升高,白蛋白由(35.7±6.1)g/L升至(39.4±5.9)g/L,血清钾由(4.1±0.7)g/L升至(4.9±0.8)g/L,P<0.01。两组治疗前后血白细胞及其它生化指标均相近。⑤静脉组2例有不良反应,其中1例轻微心悸,1例轻度胃肠道反应。口服组7例出现明显胃肠道症状。静脉组总不良反应发生率(2/25,8.0%)明显低于口服组(7/25,28.0%),P<0.01。结论①静脉注射右旋糖酐氢氧化铁可有效纠正CAPD患者的铁缺乏、提高铁利用率及EPO的治疗效果。②静脉注射右旋糖酐氢氧化铁临床应用不良反应发生率低、安全性良好。     

Soluble transferrin receptor (sTfR): biological variations and reference limits.

The aim of this study was to establish soluble serum transferrin receptor (sTfR) reference limits. sTfR was measured in 885 healthy subjects from 3 to 91 years old (433 men, 409 women), without hematological abnormalities, using an immunonephelometric assay. The sTfR median concentrations in our population decreased gradually from the group aged 3-10 years to the group aged 21-40 years, then there were no changes in the older groups except for the females >60 years of age. The interindividual variability ranged from 12.6% to 30.3% among different age groups, and the analytical variability was 5%. Biological factors and other factors associated with sTfR concentration variation were examined and accounted for 35% of the sTfR variability in men aged 20 years or less, and 18% in those older than 20 years. Also, they accounted for 45% of the variability in women aged 20 years or less and 14% in those older than 20 years. The main factors statistically associated with sTfR concentration in males were ferritin, orosomucoid, hemoglobin, and tobacco in all age groups and only mean corpuscular volume (MCV) in males less than 20 years old. In the females the main factors were age, orosomucoid, and hemoglobin in all age groups, MCV and tobacco in females less than 20 years old, and ferritin and physical activity in females more than 20 years old. These factors were used to define the exclusion and partition criteria for obtaining the reference samples. Medians for reference values were: 1.60 mg/l in the 3-10-year old group (males and females); 1.42 mg/l in males between 11 and 20 years of age, and 1.33 mg/l in females of the same age. In the other age groups, the median of the reference values was 1.16 mg/l, except in females over 60 years old, for whom it was 1.26 mg/l.     

不同年龄段儿童血清碱性磷酸酶参考区间的探讨

目的探讨0~14岁不同年龄段表观健康儿童血清碱性磷酸酶(ALP)的参考区间。方法严格筛选北京同仁医院2013年1月1日至2014年12月31日3 437例表观健康儿童(0~14岁),其中男1 989例,女1 448例。将所有筛选儿童根据年龄分为5组(0~3岁、3~6岁、6~9岁、9~12岁和12~14岁)。采用美国贝克曼库尔特DxC800全自动生化分析仪及原装试剂盒检测ALP,并对所得的结果进行统计学处理。剔除离群值后检验数据是否处于正态分布,并采用独立样本t检验比较不同性别儿童之间ALP差异,利用单因素方差分析比较不同年龄段儿童ALP的组间差异,并判断是否需按年龄、性别分组;将不需分组的进行合并,并确定实际分组。用非参数方法计算各实际分组参考区间的2.5和97.5百分位数,并计算其90%置信区间。结果不同年龄段(0~14岁)表观健康儿童ALP水平较成人明显升高,但0~3岁、3~6岁、6~9岁和9~12岁年龄段儿童无性别差异;12~14岁年龄段儿童ALP水平存在性别差异,男性ALP参考区间为105~405 U/L,女性ALP参考区间为73~275U/L。结论表观健康儿童ALP水平较成人明显升高,应建立适合不同年龄段儿童的ALP参考区间,为临床疾病的诊断、治疗提供参考依据。     

Early prediction of uteroplacental complications of pregnancy using Doppler ultrasound, placental function tests and combination testing.

In a prospective, blind study of 183 unselected women attending for routine booking scan with a singleton pregnancy at 16-24 weeks' gestation, uteroplacental resistance index, and peripheral levels of alpha-fetoprotein, human chorionic gonadotropin, human placental lactogen, Schwangerswaft protein, pregnancy-associated placental protein A and insulin-like growth factor (IGF) binding protein 1 were measured. High levels of alpha-fetoprotein and IGF 1 binding protein 1 (> 90th centile) were associated with small-for-gestational age babies (< 10th centile) (sensitivity 24% and 22%; specificity 90% and 91%). High levels of alpha-fetoprotein, human chorionic gonadotropin and pregnancy-associated placental protein A (> 90th centile) were associated with one or more of three severe complications of pregnancy: very small-for-gestational age (< 3rd centile), severe proteinuric hypertension or intrauterine death (sensitivity 20%, 20% and 57%; specificity 90%, 95% and 91%, respectively). A uteroplacental resistance index > 90th centile was also associated with small-for-gestational age and severe complications (sensitivity 24% and 50%, specificity 90% and 90%). A combination of resistance index and a placental function test improved the prediction for a group of patients that included any complications (sensitivity 31% and specificity 89%). Doppler ultrasound was a more efficient predictor than individual placental function tests but screening predictions can be improved by combining Doppler parameters and placental protein estimations. Combinations of placental function tests might provide equivalent, or complementary, information. This preliminary work demonstrates the potential value of combining biophysical and biochemical tests to predict complications of pregnancy.     

蔗糖铁治疗维持性血液透析患者不安腿综合征的临床观察

目的通过观察静脉注射蔗糖铁对维持性血液透析(maintenance hemodialysis,MHD)患者不安腿综合征(restless legs syndrome,RLS)评分的变化,探讨蔗糖铁治疗MHD患者RLS的临床疗效。方法①选择在上海市闸北区中心医院血液净化中心透析龄超过3个月的MHD患者40例,经问卷调查确诊有RLS,诊断采用RLS国际研究小组制定的标准并进行评分。②随机分为治疗组20例,对照组20例,治疗组静脉滴注蔗糖铁100mg/次,每周1次,连续用药10周,总量1000mg;对照组不用蔗糖铁以及其他铁剂。③分别观察两组患者在治疗前、治疗后4、8、10周的血红蛋白(Hb)、血清铁(Fe)、血清铁蛋白(SF)、总铁结合力、转铁蛋白饱和度(TSAT)水平的变化,同时观察患者RLS评分及药物不良反应等。结果①两组患者治疗前Hb、Fe、SF、总铁结合力、TSAT无统计学意义(P>0.05)。②治疗组随着治疗时间延长,Fe、SF、TSAT逐渐升高,治疗后4周较治疗前明显上升、且治疗后10周上升更为明显(P<0.05,P<0.01);而总铁结合力较治疗前逐渐降低、治疗后10周下降更为明显(P<0.05,P<0.01);分别与同期对照组比较,有统计学意义(P<0.05,P<0.01);对照组上述指标治疗前后无明显变化(均P>0.05)。③治疗前、治疗后4、8、10周的RLS评分,治疗组和对照组比较:治疗前为[(16.29±10.08]与(15.79±10.42)](P>0.05);第4周为[(14.02±9.18)与(16.03±10.42)](P<0.05);第8周为[(10.94±9.03)与(15.12±9.34)](P<0.01);第10周为[(10.02±8.14)与(14.97±10.13)](P<0.01);④治疗组未发生药物不良反应。结论不安腿综合征(RLS)是MHD患者常见的并发症之一,铁缺乏与RLS的发生发展有关。MHD患者常合并铁缺乏,在补铁治疗后,患者铁贮备明显升高、RLS评分亦明显下降,对治疗RLS取得一定的疗效。     

Reference distributions for the positive acute phase serum proteins, alpha1-acid glycoprotein (orosomucoid), alpha1-antitrypsin, and haptoglobin: a practical, simple, and clinically relevant approach in a large cohort

Most clinical conditions are accompanied by corresponding changes in serum levels of some, if not all, of the acute phase proteins. While conditions that affect the acute phase proteins are usually inflammatory in nature, non-inflammatory conditions also can cause changes (e.g., malnutrition, some malignancies without secondary inflammation, and genetic polymorphism). Only after the confounding effects of non-inflammatory conditions are taken into account can these measurements be used to detect and stage the inflammatory process and to evaluate the impact of treatment. In this third article in a series, reference ranges for serum levels for three of the acute phase proteins that increase during inflammation are examined: alpha1-acid glycoprotein (orosomucoid), alpha-antitrypsin, and haptoglobin. The study is based on a cohort of 55,199 Caucasian individuals from northern New England, tested in our laboratory between 1994 and 1999. Measurements were standardized against CRM 470 (RPPHS) and analyzed using a previously described statistical approach. Individuals with unequivocal laboratory evidence of inflammation (C-reactive protein of 10 mg/l or higher) were excluded. Levels of a,-acid glycoprotein changed little during life and between the sexes. Levels of alpha1-antitrypsin varied somewhat by age, rising slightly beyond age 55; males followed a pattern similar to that for females. For this protein, it was necessary to apply two equations to describe the lower levels associated with certain phenotypes. Haptoglobin levels fell significantly during the first decade of life for both males and females and climbed thereafter. Males and females displayed a similar pattern. When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution well over a broad range. When patient data are normalized in this manner, the distribution parameters can be used to assign a centile corresponding to an individual's measurement, thus simplifying interpretation.     

Serum ferritin and iron status in 'healthy' elderly individuals

Iron status, including S-ferritin, S-iron, S-transferrin, transferrin saturation and haemoglobin, was assessed in 267 selected elderly subjects (128 male, 139 female) with a median age of 79 years (range 60-93 years) not suffering from diseases connected with inappropriately high S-ferritin. In both sexes, S-ferritin levels were practically constant over the examined age range. Males had a geometric mean ferritin of 75 micrograms/l and females a value of 60 micrograms/l (p less than 0.001). Levels of S-ferritin less than 15 micrograms/l (i.e. depleted iron stores) were found in 7.8% of males and in 10.1% of females. An S-ferritin level less than 15 micrograms/l and transferrin saturation less than 15% (i.e. latent iron deficiency) was observed in 2.3% of males and in 2.2% of females. None had iron deficiency anaemia. In subjects (n = 232) without iron deficiency [i.e. S-ferritin greater than or equal to 15 micrograms/l, mean red cell volume greater than or equal to 79 fl and haemoglobin greater than or equal to 121 g/l (7.5 mmol/l)], the arithmetic mean of S-iron was 18 mumol/l. S-transferrin 28 mumol/l and transferrin saturation 33%. The levels of S-iron, S-transferrin and transferrin saturation were not significantly different in males and females.     

Reference distributions for complement proteins C3 and C4: a comparison of a large cohort to the world's literature

The lack of credible reference materials and satisfactory methods for quantifying serum levels has limited the bedside use of complement protein (C3 and C4) measurements. However, great technological strides have been made in the last few years. The remaining barrier to a more relevant and cost-effective use of serum protein data for diagnosis and prognosis is the availability of reliable reference intervals from birth to old age for both males and females. Fifty-one publications reporting reference intervals were identified that meet the criteria used in our prior four studies, and these were analyzed statistically. Previous small studies with constrained age ranges agree, on average, with our larger series of life-long reference ranges. This meta-analysis provides support for our reference ranges and places them in the context of previous publications.