Determination Of Hemoglobin Research Articles

Molecular analysis and association with clinical and laboratory manifestations in children with sickle cell anemia.

ObjectivesTo analyze the frequency of βS-globin haplotypes and alpha-thalassemia, and their influence on clinical manifestations and the hematological profile of children with sickle cell anemia.MethodThe frequency of βS-globin haplotypes and alpha-thalassemia and any association with clinical and laboratorial manifestations were determined in 117 sickle cell anemia children aged 3–71 months. The confirmation of hemoglobin SS and determination of the haplotypes were achieved by polymerase chain reaction-restriction fragment length polymorphism, and alpha-thalassemia genotyping was by multiplex polymerase chain reaction (single-tube multiplex-polymerase chain reaction).ResultsThe genotype distribution of haplotypes was 43 (36.7%) Central African Republic/Benin, 41 (35.0%) Central African Republic/Central African Republic, 20 (17.0%) Rare/atypical, and 13 (11.1%) Benin/Benin. The frequency of the α3.7 deletion was 1.71% as homozygous (−α3.7/−α3.7) and 11.9% as heterozygous (−α3.7/αα). The only significant association in respect to haplotypes was related to the mean corpuscular volume. The presence of alpha-thalassemia was significantly associated to decreases in mean corpuscular volume, mean corpuscular hemoglobin and reticulocyte count and to an increase in the red blood cell count. There were no significant associations of βS-globin haplotypes and alpha-thalassemia with clinical manifestations.ConclusionsIn the study population, the frequency of alpha-thalassemia was similar to published data in Brazil with the Central African Republic haplotype being the most common, followed by the Benin haplotype. βS-globin haplotypes and interaction between alpha-thalassemia and sickle cell anemia did not influence fetal hemoglobin concentrations or the number of clinical manifestations.

Quantification of glycated hemoglobin indicator HbA1c through near-infrared spectroscopy

A new strategy for quantitative analysis of a major clinical biochemical indicator called glycated hemoglobin (HbA1c) was proposed. The technique was based on the simultaneous near-infrared (NIR) spectral determination of hemoglobin (Hb) and absolute HbA1c content (Hb • HbA1c) in human hemolysate samples. Wavelength selections were accomplished using the improved moving window partial least square (MWPLS) method for stability. Each model was established using an approach based on randomness, similarity, and stability to obtain objective, stable, and practical models. The optimal wavebands obtained using MWPLS were 958 to 1036 nm for Hb and 1492 to 1858 nm for Hb • HbA1c, which were within the NIR overtone region. The validation root mean square error and validation correlation coefficients of prediction (V-SEP, V-R P ) were 3.4 g L-1 and 0.967 for Hb, respectively, whereas the corresponding values for Hb • HbA1c were 0.63 g L-1 and 0.913. The corresponding V-SEP and V-R P were 0.40% and 0.829 for the relative percentage of HbA1c. The experimental results confirm the feasibility for the quantification of HbA1c based on simultaneous NIR spectroscopic analyses of Hb and Hb • HbA1c.

A study of zinc, copper and iron parameters in children with cognitive impairment

Objective Zinc, copper and iron have been considered vital for normal brain functioning. Our study aimed to assess changes in the level of zinc, copper, ferritin and haemoglobin (HgB) concentration in children who presented with variable degrees of cognitive impairment. Patients and methods In this study, determination of HgB%, plasma ferritin, zinc and copper in 68 children with cognitive impairment and in 46 age-matched control children was carried out. Correlation between various elements was studied. Results A significantly decreased levels of plasma zinc and copper were found in children with cognitive decline compared with control children (P<0.0001 and P<0.0001, respectively). A significantly decreased ferritin was also found in affected children (P<0.001), whereas the difference in HgB% between both groups was not significant. No significant correlation was found between zinc and copper and between HgB% and ferritin among the studied patients, which could be attributed to increased variances of the studied elements in affected children and to the role of other cofactors. Conclusion Our current study highlights the role of zinc, copper and iron stores in cognitive processes in children, being significantly decreased in children with cognitive impairment; however, further randomized controlled studies are needed in similar populations to confirm their role.

Hemolysis, Pump Thrombus, and Neurologic Events in Continuous-Flow Left Ventricular Assist Device Recipients

An ongoing challenge in the management of patients with heart failure who receive left ventricular assist devices (LVADs) is achieving optimal anticoagulation. Adverse prothrombotic events include hemolysis or pump thrombus (H/T) and neurologic events (NEs), and all limit the success of LVAD therapy. Our aim was to study the incidence and clinical outcomes associated with these events in a large single-center cohort. We retrospectively reviewed our prospectively collected database of all patients receiving a HeartMate II (Thoratec Corp, Pleasanton, CA) LVAD from 2005 to 2012. Demographic, clinical, and outcome data were analyzed using standard statistical methods. All adverse events were recorded. Of 193 patients receiving LVADs, we identified 39 H/T events in 26 (13.4%) patients and 22 NEs in 19 (9.8%) patients. Seventy-four percent of events occurred in the last 3 years of the series, during which time 63% of implants were placed. Of patients with H/T, 8 (31% of those having H/T, 4.1% of total) had more than 1 event and 4 (15.4% of those having H/T, 2.1% of total) underwent pump exchanges. Five (23%) patients had NEs after H/T, and 6 (32%) died as a result of the NE. Of patients with H/T, 27% had preceding episodes of infection, 31%had an international normalized ratio (INR) of less than 1.5, 31% had an INR of 1.5 to 2, 15% had a history ofclotting or were hypercoagulable, and 4% had anticoagulation intentionally withheld. Lactate dehydrogenase (LDH), plasma hemoglobin, INR, and platelet determinations were significantly different at the time of H/T compared with baseline values. The survival at 6months (alive or having undergone transplantation) for those with a prothrombotic event compared with those without was 70% versus 75.2% (p= 0.5). The incidence of H/T or NEs is significant and results in major morbidity after LVAD placement. Infection and suboptimal anticoagulation are associated with the majority of these events. Identification of patients at higher risk for hemolysis (ie, infection) may allow for modification of anticoagulation regimens to reduce these risks and improve clinical outcomes.

Prevalence and severity of anaemia stratified by age and gender in rural India.

Anaemia is a major public health problem in India. Although nearly three quarters of the Indian population live in rural areas, the epidemiology of anaemia in rural settings is not well known. We performed a retrospective observational study using routine clinical data from patients attending the out-patient clinics of a rural hospital in India from June 2011 to August 2014. The study included 73,795 determinations of haemoglobin. 49.5% of patients were female. The median haemoglobin concentration was 11.3 g/dL (interquartile range (IQR), 9.8–12.4) in females and 12.5 g/dL (IQR, 10.6–14.2) in males. Anaemia was present in the majority of children <10 years, women after puberty, and older adults. Children <5 years had the highest prevalence of anaemia, especially children aged 1-2 years. The high proportion of microcytic anaemia and the fact that gender differences were only seen after the menarche period in women suggest that iron deficiency was the main cause of anaemia. However, the prevalence of normocytic anaemia increased with age. The results of this study can be used by public health programmes to design target interventions aimed at reducing the huge burden of anaemia in India. Further studies are needed to clarify the aetiology of anaemia among older adults.

Analysis of the Results on Perioperative Blood Loss after a Total Knee Arthroplasty Employing Tranexamic Acid before or after Inflating the Tourniquet

Introduction: Tranexamic acid has showed its good results reducing blood loss in total knee arthroplasties. It has also probed being cost-effective (red cell concentrate: 350 euros/ TXA vial 3, 05 euros) but it remains not being clear at what time during the surgery we have to administrate it. In this prospective, randomized study, we have investigated the effects of the use of tranexamic acid before or after inflating the tourniquet on blood loss, transfusion needs and thromboembolic complications after implanting a total knee arthroplasty. 120 patients were selected and assigned randomly in two groups: tranexamic acid employed before inflating (group 1) or just before deflating the tourniquet (Group 2). Methods and Materials: From May 2011 to May 2012, 80 patients (38 males, 42 females; aged 64-81 years, mean age 69, 2years) underwent to a total knee replacement. All of them had moderate-severe knee osteoarthritis. They were randomized divided into Group1 and Group 2 of 40 patients each. The patients in Group 1 received tranexamic acid (TXA) before inflating the tourniquet and TXA was administered on the patients in Group 25 minutes before deflating the tourniquet. TXA was used in both groups every 8 hours during the first three days postop. Variables under comparison included haemoglobin determinations (pre, postop and fifth days after surgery), drainage blood volume, transfusion requirements and appearance of thromboembolic complications. Results: The drainage blood loss was 364 ± 186 ml (Group 1) and 413 ± 175 ml (Group 2).The total blood loss was 573 ± 159 ml (Group 1) and 608 ± 132 (Group 2). No statistical significant differences were found in the amount of blood at the drain and on the total blood loss.The haemoglobin values did not showed statistical significant differences between groups before surgery on the postop or 5 days after the surgery. No significant difference in haemoglobin determinations (pre, postop and fifth days after surgery), drainage blood volume, transfusion requirements, deep-vein thrombosis, and pulmonary embolism was detected between the groups. One patient in group 1 received 1 unit of allogenic blood and one patient in group 2 received 3 units. No statistical significant difference was seen.Two patients in group 1 and three patients in group 2 had clinical symptoms of deep vein thrombosis. Only one patient in group 2 presented an eco-Doppler study positive for a lower limb thrombosis. Conclusions: We conclude that there is no significant difference on blood loss, transfusion requirements and thromboembolic complications after performing a total knee arthroplastywhen thetranexamic acid is employed before inflating or just before releasing the tourniquet.

Serum Zinc Deficiency and Associated Factors among Pre-ART and on-ART Adults at Felege Hiwot Referral Hospital, Bahir Dar, Northwest Ethiopia

Background: Among several trace elements, zinc is a micronutrient that has a very significant role in maintaining immune function. Studies investigating trace elements status in people living with HIV/AIDS are few in Ethiopia. Hence, the present study was undertaken to investigate the concentration of serum zinc among sex and age matched pre ART and on ART adults. Methods: A cross-sectional study was conducted among 150 people living with HIV/AIDS (75 pre -ART and 75 on -ART) adults. Concentrations of zinc from serum were measured using fully automated flame atomic absorption spectrophotometer. CD4+ T-cell count, CD8+ T-cell count, hemoglobin determination, and Body Mass Index (BMI) were performed to evaluate the clinical status of study participants. Results: Serum zinc deficiencies were observed in 46 (30.7%) study participants. In multivariate logistic regression analysis, pre-ART study participants were nearly four times more likely at risk of serum zinc deficiency than on-ART study participants (AOR=3.56, 95% CI=1.52 to 8.32). Similarly, the odds of being serum zinc deficient were three times more in undernourished study participants than nourished study participants (AOR=2.61, 95% CI=1.02 to 6.67). Conclusion: A relatively high percentage of study participants had serum zinc deficiency. Early evaluation of serum zinc deficiency and zinc supplementation along with anti-retroviral treatment should be considered for pre-ART and under nourished adult people living with HIV/AIDS.

The Free Alpha-Hemoglobin: A Promising Biomarker for β-Thalassemia

The purpose is to review the current knowledge and methods of determination of the free alpha hemoglobin with emphasis on its potential implications in patients with beta-thalassemia (β-thal).The severity of β-thal correlates with the extent of imbalance between α- and non-α-globin chains and the amount of the free alpha hemoglobin (free α- Hb) pool in the erythrocytes. To date, there is a lack of biomarkers that convey diagnostic and prognostic values in β-thal. Our ongoing research is aimed to evaluate the potential prognostic and diagnostic implications of free α-Hb to improve the care of patients with β-thal. Our ongoing research is aimed to quantify the free α-Hb for its potential prognostic and diagnosticimplications towards improving the care of patients with various β-thal types in the years to come.

Combined reflectance spectroscopy and stochastic modeling approach for noninvasive hemoglobin determination via palpebral conjunctiva.

A combination of stochastic photon propagation model in a multilayered human eyelid tissue and reflectance spectroscopy was used to study palpebral conjunctiva spectral reflectance for hemoglobin (Hgb) determination. The developed model is the first biologically relevant model of eyelid tissue, which was shown to provide very good approximation to the measured spectra. Tissue optical parameters were defined using previous histological and microscopy studies of a human eyelid. After calibration of the model parameters the responses of reflectance spectra to Hgb level and blood oxygenation variations were calculated. The stimulated reflectance spectra in adults with normal and low Hgb levels agreed well with experimental data for Hgb concentrations from 8.1 to 16.7 g/dL. The extracted Hgb levels were compared with in vitro Hgb measurements. The root mean square error of cross‐validation was 1.64 g/dL. The method was shown to provide 86% sensitivity estimates for clinically diagnosed anemia cases. A combination of the model with spectroscopy measurements provides a new tool for noninvasive study of human conjunctiva to aid in diagnosing blood disorders such as anemia.

Evaluation of noninvasive hemoglobin measurements in trauma patients

BackgroundReliable, accurate, noninvasive, and continuous determination of hemoglobin would be an important advance in the care of trauma patients. The aim of this study was to evaluate the utility of the Masimo Radical 7 device in severely injured trauma patients. MethodsHighest level trauma activation patients were enrolled over a 1-year period. Laboratory hemoglobin values were compared with Masimo hemoglobin values using Bland-Altman analysis. ResultsA total of 525 patients were enrolled in the study. Comparison of 861 paired values from 418 patients showed a variance of 3.89 to −3.84 g/dL, showing a nonsignificant correlation between Masimo hemoglobin and laboratory hemoglobin values. ConclusionsThe Masimo Radical 7 system evaluated in this study holds promise, but it is not ready to be used as an initial noninvasive evaluation tool in the acute treatment of severely injured trauma patients. There was a poor correlation between Masimo hemoglobin and laboratory hemoglobin and large numbers of missing data. On the basis of the poor correlation, the Masimo Radical 7 device cannot currently be used to guide transfusion therapy.

A novel fluorescence assay for the detection of hemoglobin based on the G-quadruplex/hemin complex

A novel sensing strategy for specific recognition of hemoglobin has been designed. In the presence of trypsin, hemoglobin was cleaved to release heme which could effectively bind to a FITC-labeled guanine (G)-rich oligonucleotide sequence to form the G-quadruplex/hemin complex. This binding process would lead to fluorescence quenching of FITC via photoinduced electron transfer. Therefore, a fluorescence assay for the determination of hemoglobin could be established. Under the optimized conditions, there was a linear relationship between the fluorescence intensity of probe DNA and the hemoglobin concentration in the range of 5-200 nmol/L, with the limit of detection (LOD) as low as 2 nmol/L.

Microwaving Blood as a Non‐Destructive Technique for Haemoglobin Measurements on Microlitre Samples

The non-destructive ex vivo determination of haemoglobin (Hgb) concentration offers the capability to conduct multiple red blood cell haematological measurements on a single sample, an advantage that current optical techniques are unable to offer. Here, a microwave method and device for the accurate and non-destructive determination of Hgb concentration in microlitre blood samples are described. Using broadband microwave spectroscopy, a relationship is established between the dielectric properties of murine blood and Hgb concentration that is utilized to create a technique for the determination of Hgb concentration. Subsequently, a microwave dielectric resonator-microfluidic system is implemented in the analysis of 52 murine samples with microlitre volumes and Hgb concentrations ranging from 0 to 17 g dL(-1) . Using the characterized relationship, independent and minimally invasive Hgb measurements are made on nine healthy mice as well as seven with mutations in the Adenomatous polyposis coli (APC) gene that leads to colorectal cancer and consequently anaemia.

Facile synthesis of N-acetyl-l-cysteine capped CdHgSe quantum dots and selective determination of hemoglobin

Using N-acetyl-l-cysteine (NAC) as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared NAC capped CdHgSe quantum dots were thoroughly characterized by fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. A novel method for the selective determination of hemoglobin (Hb) was developed based on fluorescence quenching of the NAC capped CdHgSe quantum dots. A number of key factors including pH value of phosphate buffer solution, quantum dots concentration, the adding sequence of reagents and reaction time that influence the analytical performance of the NAC capped CdHgSe quantum dots in Hb determination were investigated. Under the optimal experimental conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of Hb in the range of 4.0×10−9–4.4×10−7molL−1 with a detection limit of 2.0×10−9molL−1. The developed method has been successfully employed to determine Hb in human urine samples.

Clinical significance of glycosylated hemoglobin determination on diabetic cataract surgery

Clinical significance of glycosylated hemoglobin determination on diabetic cataract surgery

Can the Roche hemolysis index be used for automated determination of cell-free hemoglobin? A comparison to photometric assays

ObjectivesThe aim of this study was to develop a novel method for automated quantification of cell-free hemoglobin (fHb) based on the HI (Roche Diagnostics). MethodsThe novel fHb method based on the HI was correlated with fHb measured using the triple wavelength methods of both Harboe [fHb, g/L=(0.915 * HI+2.634)/100] and Fairbanks et al. [fHb, g/L=(0.917 * HI+2.131)/100]. fHb concentrations were estimated from the HI using the Roche Modular® automated platform in self-made and commercially available quality controls, as well as samples from a proficiency testing scheme (INSTAND). The fHb using Roche automated HI results were then compared to results obtained using the traditional spectrophotometric assays for one hundred plasma samples with varying degrees of hemolysis, lipemia and/or bilirubinemia. ResultsThe novel method using automated HI quantification on the Roche Modular® clinical chemistry platform correlated well with results using the classical methods in the 100 patient samples (Harboe: r=0.9284; Fairbanks et al.: r=0.9689) and recovery was good for self-made controls. However, commercially available quality controls showed poor recovery due to an unidentified matrix problem. ConclusionsThe novel method produced reliable determination of fHb in samples without interferences. However, poor recovery using commercially available fHb quality control samples currently greatly limits its usefulness.

Accuracy of noninvasive hemoglobin and invasive point‐of‐care hemoglobin testing compared with a laboratory analyzer

IntroductionHemoglobin concentration is assessed to detect anemia and its associated morbidities. Hemoglobin is usually determined from venous or capillary blood samples run on a laboratory analyzer. However, this method requires a needle stick and results can be delayed. It also exposes caregivers to risks associated with needle sticks and blood exposure. Noninvasive hemoglobin determination would be of benefit to patients and caregivers because it would allow for quick and painless point-of-care assessment.MethodsHemoglobin determination from a noninvasive spot check hemoglobin device (Pronto-7 with SpHb, Masimo) and an invasive point-of-care device (HemoCue) was compared with venous blood samples run on a laboratory hematology analyzer.ResultsA total of 440 outpatients and healthy volunteers were included (mean age 36 years, 62% female). Compared with the hematology analyzer, the bias ± standard deviation of was −0.1 ± 1.1 g/dL for SpHb and −0.1 ± 1.6 g/dL for HemoCue.ConclusionNoninvasive hemoglobin testing with SpHb provided similar accuracy as invasive point-of-care hemoglobin testing and may enable more efficient and effective patient care.

Label-Free Detection of Hemoglobin Using MWNT-Embedded Screen-Printed Electrode

The synthesis of a network of cross-linked multiwalled carbon nanotubes (MWNTs) on a cysteamine-functionalized screen-printed gold electrode (MWNT/Au-SPE) and its use as a sensor for hemoglobin (Hb) determination is reported. It is proved to be a ready-to-use platform for routine clinical analysis in the blood after the separation of red blood cells. The study shows direct electron transfer between Hb-FeIII and Hb-FeII on applying a potential difference which is beneficial in detecting the presence of Hb in solution. The characterization of MWNT-embedded electrode was accomplished through Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy (EIS), Raman spectroscopy, optical profiling, and cyclic voltammetry. EIS studies show a reduction in the value of surface charge transfer resistance (Rct) from MWNT/Au-SPE (−2.72 kΩ) to bare Au-SPE (−24.38 kΩ), respectively. MWNT/Au-SPE showed better electrochemical characteristics, and kinetic studies revealed the heterogeneous rate transfer constant (ks) of 1.26 s−1. The electrochemically active surface area was also increased 100 times from bare Au-SPE (2.41 × 10−6 cm2) to MWNT/Au-SPE (2.052 × 10−4 cm2). The sensitivity of the sensor for Hb determination was found to be 20.50 μA g−1 dl in the linear range of 9–15 g dl−1 for lyophilized Hb. It is also found to be extremely sensitive for Hb determination in blood samples with 38.75 μA g−1 dl sensitivity in the same linear range.

A high prevalence of zinc- but not iron-deficiency among women in rural Malawi: a cross-sectional study.

Zinc deficiency is often associated with nutritional iron deficiency (ID), and may be exacerbated by low selenium status. To investigate risk of iron and zinc deficiency in women with contrasting selenium status. In a cross-sectional study, 1-day diet composites and blood samples were collected from self-selected Malawian women aged 18-50 years from low- (Zombwe) (n=60) and high-plant-available soil selenium (Mikalango) (n=60) districts. Diets were analyzed for trace elements and blood for biomarkers. Zinc deficiency (>90 %) was greater than ID anemia (6 %), or ID (5 %), attributed to diets low in zinc (median 5.7 mg/day) with high phytate:zinc molar ratios (20.0), but high in iron (21.0 mg/day) from soil contaminant iron. Zombwe compared to Mikalango women had lower (p<0.05) intakes of selenium (6.5 vs. 55.3 µg/day), zinc (4.8 vs. 6.4 mg/day), iron (16.6 vs. 29.6 mg/day), lower plasma selenium (0.72 vs. 1.60 µmol/L), and higher body iron (5.3 vs. 3.8 mg/kg), although plasma zinc was similar (8.60 vs. 8.87 µmol/L). Body iron and plasma zinc were positive determinants of hemoglobin. Risk of zinc deficiency was higher than ID and was shown not to be associated with selenium status. Plasma zinc was almost as important as body iron as a hemoglobin determinant.

Association of anemia and renal function test among diabetes mellitus patients attending Fenote Selam Hospital, West Gojam, Northwest Ethiopia: a cross sectional study

BackgroundAnemia is a common problem in diabetic patients. Diabetic patients have a greater severity of anemia as the level of Glomerular Filtration Rate (GFR) decreases compared to non-diabetic patients. Despite these facts, anemia is unrecognized and largely untreated in patients with diabetes in Ethiopia particularly in those patients attending Fenote Selam Hospital. Therefore, this study was aimed to assess the association of anemia and renal function test among diabetes mellitus patients attending Fenote Selam Hospital, North West of Ethiopia.MethodsAn Institutional -based cross-sectional study was conducted from February 2012 to April 2012 on diabetes mellitus (DM) patients. Systematic random sampling technique was used to get the total sample size of 384 patients. A total of seven ml of venous blood was collected from diabetes mellitus patients; two ml was collected by EDTA anticoagualted vacutainer test tube for haemoglobin determination and 5 ml venous blood was collected by plain vacutainer tube for creatinine and Blood urea nitrogen determination. The data were double entered and analyzed using SPSS-16 statistical software. The degree of association between independent and dependent variables was assessed using bivariate and multivariate logistic regression analysis in terms of P-value and odds ratio with 95% confidence interval.ResultsOut of the total 384 DM patients included in the study 73 (19%) were anemic. Fifty three (13.8%), forty eight (12.5%), and two hundred eighty three (73.7%) DM patients had an estimated GFR <60 ml/min/1.73 m, 60 – 90 ml/min/ 1.73 m, and > 90 ml/min/1.73 m respectively. One hundred eleven (28.9%) diabetic patients had increased urine albumin level. There was a statistically significant association between anaemia and Glomerular filtration rate (P<0.05) with Odds ratio of 8.58 and CI (10.21, 49.94). As the glomerular filtration rate increase, the risk to be anemic will decrease dramatically.ConclusionThe study showed that there was a significant association between anaemia and Glomerular filtration rate in DM patients. Therefore, DM patients should be strictly monitored for renal failure and anemia for proper management of diabetes patients.

Parathyroid hormone ablation alters erythrocyte parameters that are rescued by calcium‐sensing receptor gene deletion

The mechanisms by which parathyroid hormone (PTH) produces anemia are unclear. Parathyroid hormone secretion is regulated by the extracellular Ca2+ -sensing receptor. We investigated the effects of ablating PTH on hematological indices and erythrocytes volume regulation in wild-type, PTH-null, and Ca2+ -sensing receptor-null/PTH-null mice. The erythrocyte parameters were measured in whole mouse blood, and volume regulatory systems were determined by plasma membrane K+ fluxes, and osmotic fragility was measured by hemoglobin determination at varying osmolarities. We observed that the absence of PTH significantly increases mean erythrocyte volume and reticulocyte counts, while decreasing erythrocyte counts, hemoglobin, hematocrit, and mean corpuscular hemoglobin concentration. These changes were accompanied by increases in erythrocyte cation content, a denser cell population, and increased K+ permeability, which were in part mediated by activation of the K+ /Cl- cotransporter and Gardos channel. In addition we observed that erythrocyte osmotic fragility in PTH-null compared with wild-type mice was enhanced. When Ca2+ -sensing receptor gene was deleted on the background of PTH-null mice, we observed that several of the alterations in erythrocyte parameters of PTH-null mice were largely rescued, particularly those related to erythrocyte volume, K+ fluxes and osmotic fragility, and became similar to those observed in wild-type mice. Our results demonstrate that Ca2+ -sensing receptor and parathyroid hormone are functionally coupled to maintain erythrocyte homeostasis.