Determination Of Calcium In Serum Research Articles

METABOLIC ABNORMALITIES IN PATIENTS WITH CALICEAL DIVERTICULAR CALCULI

Purpose We determined the incidence and spectrum of metabolic abnormalities in patients with caliceal diverticular calculi. Materials and Methods Five men and 9 women with caliceal diverticular calculi underwent metabolic evaluation, including determination of serum electrolytes, calcium, phosphate and uric acid, and 24-hour urinary volume, creatinine, calcium, oxalate, uric acid and citrate. Results Of the 14 patients 7 (50%) had urinary excretion abnormalities promoting stone formation, including hypercalciuria in 3, hyperoxaluria in 1, hypercalciuria combined with hyperuricosuria in 1 and hyperoxaluria combined with hyperuricosuria in 2. Two patients had a history of gout while another had radiographic evidence of medullary sponge kidney. Of the patients 9 (64.3%) had a history of synchronous or metachronous calculi distant from the involved caliceal diverticular stone and 5 (55.6%) of these 9 had definable metabolic disorders. However, there was no statistically significant difference in urinary excretion values between patients with or without a history of additional extra diverticular stones. Conclusions Urinary stasis alone does not explain stone formation in a significant number of patients with caliceal diverticular calculi. Rather, the local physiological environment of the urine likely has a predisposing role and evaluation for metabolic abnormalities should be considered. In some patients cure may be effected by treating the stone and any associated metabolic disorders rather than the diverticulum.

The Application of Partial Least Squares Method (PLS) for Simultaneous Spectrophotometric Determination of Calcium and Magnesium in Human Serum

Summary Application of a partial least squares algorithm (PLS-1) is proposed in this work for simultaneous spectrophotometric determination of calcium and magnesium in human serum. Two chromogenic agents, Calmagite [1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphtol-4-sulfonic acid] and o-Cresolphtalein [3′,3″-bis{[bis-(carboxymethyl)amino]methyl}-5′5″-dimethylphenolphtalein] were used, which form color complexes with the two elements studied. As expected, significant interferences were observed for the individual methods (Ca-o-Cresolphtalein and Mg-Calmagite) in the presence of the second metal. However, applying a full-spectrum chemometric method PLS-1, it was possible to eliminate these interferences in the calibration step and satisfactory prediction results were obtained for calcium and magnesium in real serum samples. The proposed procedure was validated using Refererence Serum (171760 Boehringer Mannheim, Germany). The analytical results obtained for human serum were compared with the results of AAS determination.

Validation of candidate reference methods based on ion chromatography for determination of total sodium, potassium, calcium and magnesium in serum through comparison with flame atomic emission and absorption spectrometry

Objectives: We report on the validation of candidate reference methods based on ion chromatography for the determination of total sodium, potassium, calcium, and magnesium in serum. The current study is a continuation of previous investigations in which we were able to show the potential of ion chromatography to serve as a reference method principle. The validation consisted of comparison of the ion chromatographic methods with generally recognized reference methods based on flame atomic emission (for sodium/potassium) and absorption (for calcium/magnesium) spectrometry. Methods: Sample preparation consisted of acidic dilution and pre-purification with reversed phase cartridges. Ion chromatography with suppressed conductivity was performed with polymeric stationary phases chemically modified with carboxylate and sulfonate functional groups for sodium/potassium and calcium/magnesium, respectively. Single-point calibration was used in combination with individual adaptation of serum sampling and diluting to give similar responses in samples and standards. In the study, more than 25 control sera were analyzed in parallel with the ion chromatographic methods and the traditional reference methods. The measurement protocol consisted of quadruplicate analysis of each sample per run, in 3 different runs. In each measurement series, internal quality control with certified reference materials from the National Institute of Standards and Technology and the Bureau Communautaire de Référence was applied. The performance criteria to fulfill were predefined ( i.e., the maximum within-day and overall coefficient of variation, the confidence interval, the daily and overall deviation from the certified value and the maximum total analytical error). Results: The comparison is presented as difference plot ( i.e., deviation of the results obtained with ion chromatography from those obtained with the respective traditional reference methods). The mean deviations were +0.9% for sodium, +1.0% for potassium, ±0.0% for calcium, and +0.1 % for magnesium. With the exception of 2 values each for sodium and potassium, all deviations were within the limit of 2 times the allowed total analytical error. From the data obtained for internal quality control during the different measurement campaigns, we further estimated the long-term precision and accuracy of our methods. The overall coefficient of variation (respectively the bias) amounted to 0.7% (+0.1%) for sodium, 0.9% (−0.3%) for potassium, 1.3% (−0.1 %) for calcium, and 1.0% (±0.0%) for magnesium. Conclusion: From the precision and accuracy reached by our ion chromatographic methods, we conclude that they can be proposed as candidate reference methods for the determination of total sodium, potassium, calcium, and magnesium in serum.

Evaluation of total/near-total thyroidectomy in a short-stay hospitalization: safe and cost-effective.

Once the decision of perform total/near-total thyroidectomy has been made, common perioperative management strategies include frequent postoperative laboratory determinations, bedside airway adjuncts, and hospital stays of about 3 days. We propose a regimen for safe, cost-effective, short-stay total/near-total thyroidectomy. One hundred fifty total/near-total thyroidectomies performed between 1991 and 1994 were studied to test our short-stay thyroidectomy regimen. Patients were admitted the day of operation and observed overnight. Serum calcium values were obtained at 8, 14, and 20 hours after operation. Twenty-three-hour discharge criteria included no wound or airway problems, stable vital signs, tolerance of normal diet and activity, and an upsloping serum calcium curve. Of 150 patients undergoing total/near-total thyroidectomy, 145 (97%) met 23-hour discharge criteria. No deaths (0%) occurred. Overall morbidity (six patients [4%)]) included one (0.7%) patient with postoperative hemorrhage, one (0.7%) patient with recurrent laryngeal nerve injury, three (2%) patients with transient hypocalcemia, and one (0.7%) patient with permanent hypocalcemia. Average length of stay was 1.06 days. Significant airway and wound problems rarely develop beyond the first 12 to 18 hours after total/near-total thyroidectomy. Serial serum calcium determinations used to construct a three-point calcium curve at 20 hours after operation can reliably and safely identify patients at risk to have clinically significant hypocalcemia. Total/near-total thyroidectomy can be performed safely in a short-stay, 23-hour hospitalization setting with substantial cost savings.

Histopathological Diagnosis of Parathyroid Diseases

Hyperparathyroidism is the predominant disease of the parathyroid gland. This disease is nowadays quite common and is often diagnosed at an earlier stage, mainly by means of serum calcium determinations on wide indications. This means that when detected, the glandular abnormalities may be less advanced, which could hamper differentiation of adenoma from chief cell hyperplasia, and of normal glands from slightly hyperplastic ones. Normal glands and pathological glands both show wide variations in size, cellular composition and arrangement, as described in this article. The usefulness of applying fat staining to distinguish between normal and abnormal glands is also reported. It is important to bear in mind that the parathyroid diagnosis is in fact an indirect diagnosis based on the assessment of an associated gland or glands.

Effects of long-term use of high-dose inhaled steroids on bone density and calcium metabolism

Background: Inhaled steroids are the mainstay in the antiinflammatory treatment of asthma. In the last few years, these agents have been used in increasing doses. Because high doses of inhaled steroids can reduce serum osteocalcin levels, there are concerns regarding their long-term effects on bone metabolism. Methods: We examined the effects of doses of 800 μg/day or greater of beclomethasone or budesonide for more than 18 months in 37 asthmatic subjects (group A), matched to a control group of 37 asthmatic subjects using little or no inhaled steroids (<500 μg, group B). All had a clinical evaluation, measurements of expiratory flows, and determination of serum creatinine, calcium, phosphate, γ-glutamyl transpeptidase, alkaline phosphatase, cortisol, and osteocalcin levels. A 2-hour urinary sample was obtained for creatinine, calcium, phosphate, hydroxyproline, and cortisol measurements. Bone density was assessed at the lumbar spine level and at the hip with a Hologic-QDR-2000 osteodensitometer (Hologic, Boston, Mass.). Results: The mean (±SD) daily dose of inhaled steroids over the last 2 years was 1140 ± 353 μg in group A (mean duration of use of >800 μg/day, 34.2 ± 13.0 months) and 89 ± 98 μg for group B (mean duration of use of <500 μg/day, 15.7 ± 18.8 months). The number of oral steroid treatments (<15 days) during the last 2 years was small in the two groups, 0.92 ± 1.27 in group A and 0.05 ± 0.23 in group B ( p > 0.05). The only differences between our two groups in terms of serum or urinary parameters were for mean osteocalcin level, which was lower in group A (2.16 ± 1.09 ng/ml) than in group B (2.70 ± 0.98 ng/ml) ( p = 0.029), and in mean urinary phosphorous level, which was higher in group A (1.44 ± 0.76 mmol/2 hr) than in group B (1.26 ± 0.89 mmol/2 hr ( p = 0.034). Mean urinary hydroxyproline levels were 15.51 ± 6.98 μmol/2 hr in group A and 13.53 ± 7.13 μmol/2 hr in group B ( p > 0.05). Mean mineral bone densities of the lumbar spine and hip were similar in the two groups with values of 0.923 ± 0.136 gm/cm 2 and 0.719 ± 0.147gm/cm 2 in group A and 0.933 ± 0.154 gm/cm 2 and 0.694 ± 0.095 gmlcm 2 in group B ( p > 0.05). The T and Z scores for lumbar spine were − 1.32 ± 1.22 and −0.85 ± 1.02 in group A and −1.19 ± 1.33 and −0.72 ± 1.08 in group B ( p > 0.05). There was no correlation between the duration or dose of steroid use and bone density or osteocalcin. Although the serum osteocalcin level was lower in the group of subjects using high-dose inhaled steroids, suggesting an osteoblastic depression, bone density was not significantly different compared with the control group. Conclusions: This study shows that although the serum osteocalcin level was lower and the urinary phosphorus level was higher in subjects using high-dose inhaled steroids for a mean of 34 months, compared with a control group, no significant difference in bone density or other markers of bone metabolism was found between the two groups.

Ion chromatography as potential reference methodology for the determination of total calcium and magnesium in human serum.

The potential of ion chromatography to serve as a new reference method principle for the determination of total calcium and magnesium in human serum was investigated. Sample pretreatment consisted of acidic dilution and filtration. Detection was based on conductivity. Mean total coefficients of variation for calcium and magnesium were respectively 0.91% and 1.20% and the mean method bias was +0.06% for calcium and -0.35% for magnesium, as determined with five control materials from the Community Bureau of Reference and the National Institute of Standards and Technology. These results were comparable to those of the proposed candidate reference methods based on flame atomic absorption spectrometry. Therefore, we consider ion chromatography as a valuable reference methodology for the determination of total calcium and magnesium in human serum.

New reagent for colorimetric assay of calcium in serum

We report a new single-reagent colorimetric assay for the determination of calcium in serum. The assay is based on a novel chromogenic tetracarboxylic acid chelating agent. The method has several advantages over the o-cresolphthalein complexone (CPC) method, including improved linearity, better accuracy, increased stability, and lower working pH (9.0). The calibration curve for the assay is linear up to 4 mmol/L. The results for 47 patients' samples correlated well with results obtained with an Instrumentation Laboratory atomic absorption spectrophotometer. The mean (+/- SD) calcium values for the new method were 2.27 +/- 0.06 mmol/L and 2.26 +/- 0.05 mmol/L for the comparison method. The on-system stability of the reagents is 1 week vs 8 h for the CPC method.

Calcium determination in serum with stable alkaline Arsenazo III and triglyceride clearing

We describe an analytical procedure for determining serum calcium, using the ligand Arsenazo III in an aqueous alkaline medium. The choice of pH for the proposed technique differs from current procedures, which are for the most part carried out in a slightly acidic medium. An acidic medium avoids interference from magnesium, but is spectrophotometrically suboptimal for this pH-dependent reaction: the molar absorptivity of the Arsenazo III complex with calcium at acid pH is 13,787 L mol-1 cm-1, about one-half of that at a more optimal alkaline pH (26,574 L mol-1 cm-1). We have included a clearing technique in the reagent to avoid spectral aberrations from hypertriglyceridemic samples. alpha-Cyclodextrin absorbs the nonesterified fatty acids liberated from triglycerides by a microbial lipase. This modification may also be helpful for binding nonesterified fatty acids, which are known to interfere with calcium procedures by forming calcium soaps and thus preventing the reaction with intended ligands. The use of 8-hydroxyquinoline sulfonate as the magnesium-masking agent facilitates the use of alkaline pH. The less-water-soluble alternative, 8-hydroxyquinoline, commonly used as a precipitating agent for several methods, is difficult to solubilize in the alkaline reagent and tends to precipitate when complexed to magnesium. Finally, the use of alkaline pH results in a prolonged (> or = 6 weeks) shelf life for the reagent.

Primary hyperparathyroidism in Austria: Results of an 8‐year prospective study

Serum calcium determinations in 45,217 hospitalized patients during an 8 year period revealed sustained hypercalcemia in 124 (0.3%) patients. Further clinical and biochemical investigations established primary hyperparathyroidism (PHP) in at least 40 (32%) patients, an incidence of PHP of 89.6 +/- 41.5 per 100,000 patients per year. The incidence of PHP in males and females was 31.5 and 124.2 per 100,000, respectively. The highest incidence was found in females greater than 66 years of age (268.8 per 100,000). Nineteen (48%) patients showed classical symptoms of PHP, 14 (35%) patients were minimally symptomatic, and 7 (17%) patients were asymptomatic. The incidence and symptomatology of PHP in Austria is nearly the same as in other countries. Because of the multiple actions of parathyroid hormone in the body, PHP can cause debilitating symptoms but too often it remains undiagnosed clinically. Routine calcium determinations are very important and PHP must always be considered in the differential diagnosis, especially in minimally symptomatic patients.

Single Stable Reagent (Arsenazo III) for Optically Robust Measurement of Calcium in Serum and Plasma

We describe a method based on a single stable reagent for the determination of calcium in serum and plasma with use of Arsenazo III, 200 mumol/L in 50 mmol/L 1,4-piperazinediethanesulfonic acid (PIPES) buffer. The method showed significant positive interference in plasma at pH less than 6.6 because of the precipitation of fibrinogen, which was eliminated by increasing the pH to 6.8. The assay showed no interference from as much as 600 mumol of bilirubin and 12 g of hemoglobin per liter when applied in a simple monochromatic procedure at 660 nm. The standard curve for calcium was linear from 0 to 5.0 mmol/L. Addition of Intralipid at concentrations greater than 3 g/L demonstrated positive interference, which could be eliminated by using a 700-nm blanking wavelength. The procedure showed good agreement with all-method mean values from two external quality-control schemes.

Management of hyperparathyroid patients with grave hypercalcemia

During recent years the total number of patients undergoing surgery for hyperparathyroidism has markedly increased, but the annual number of cases with substantial hypercalcemia has remained unchanged. Parathyroid carcinoma and water clear cell hyperplasia cause more severe hypercalcemia than other kinds of hyperparathyroidism. Grave hypercalcemia due to hyperparathyroidism is more common among the elderly, but can occur during pregnancy and also among children. Occasionally, a patient with hyperparathyroidism can also have another cause of the hypercalcemia and does not become normocalcemic until adequately treated for both. The suspicion of grave hypercalcemia should arise due to its clinical features. Determination of serum calcium and intact parathyroid hormone concentrations establishes the diagnosis. The basic treatment of grave hypercalcemia is to rehydrate the patient and to restore the sodium losses. To further lower the serum calcium value we have found bisphosphonates to be very effective. The definitive treatment of grave hypercalcemia due to hyperparathyroidism is surgery. As a last resort, frail patients with grave hyperparathyroidism can undergo surgery under local anesthesia. Repeat operations can improve the prognosis of patients with metastatic parathyroid carcinoma. Selective venous catheterization with blood sampling for determination of intact parathyroid hormone can be helpful in localizing recurrent disease.

Journal of Bone and Mineral Research

Over the last 25 years, the perceived clinical spectrum of primary hyperparathyroidism (HPT) has changed dramatically from a disorder characterized by severe bone and renal disease to one typically manifested by few or mild symptoms and little evidence of organ damage. Reasons for this change in spectrum include changing demographics (primary HPT is primarily a disease of the middle-aged and elderly), diffusion of medical knowledge leading to a higher index of suspicion, and improved clinical laboratory technology (especially inexpensive and accurate determination of serum calcium and parathyroid hormone). In the first 343 cases of primary HPT seen at the Massachusetts General Hospital, 57% had renal stones, 23% had hyperparathyroid bone disease, and less than 1% had no symptoms. By contrast, studies dating from the availability of automated serum calcium measurement found renal stones and hyperparathyroid bone disease in less than 5% of cases, and about half of cases had few or no symptoms. Most patients with primary HPT today have mild, nonspecific symptoms, such as weakness, fatigue, and mental depression, and such signs as arterial hypertension and osteopenia, and detection of their hypercalcemia is generally serendipitous. The mildness and slow progression seen in many cases of primary HPT has resulted in much controversy about appropriate management.

Enzymatic clearing of lipemic serum for the determination of serum calcium

An on-line enzymatic clearing technology has been incorporated into a serum arsenazo Ill-based calcium procedure that eliminates the optical aberrations caused by hypertriglyceridemia. Lipase and a fatty acid scavenging agent, α-cyclodextrin, are added to an arsenazo III reagent at pH 6.6. At 37 °C, using a 1:67 sample to reagent ratio, clarification is complete within 4 min of incubation. The absorbance of the calcium-arsenazo III complex is measured at 650 nm versus a reagent blank. The within-run precision was 2.3% and between-run precision was 3.9%.

Potentiometric method for the determination of calcium in blood serum

A procedure for the determination of calcium in serum based on the complexation of calcium by a fixed amount of iminodiacetate at pH 9.6 with detection with a calcium-selective electrode is described. The effect of common concomitants was investigated; no interference was observed. When the procedure was tested on control sera, the bias was < 3% (6–8 replicate measurements); the relative standard deviation was < 5%.

Subcutaneous Fat Necrosis of the Newborn and Idiopathic Hypercalcemia

A newborn with important signs of fetal disturbance and respiratory distress and respiratory distress developed plaques on both buttocks 14 days after birth, with the clinical and histological characteristics of subcutaneous fat necrosis of the newborn. Fifteen days after the onset of the cutaneous signs, a discrete degree of hypercalcemia was detected. Its outcome was favorable due to the early establishment of a diet rich in medium-chain triglycerides and devoid of calcium and vitamin D. Sixteen cases of idiopathic hypercalcemia in newborn with subcutaneous fat necrosis have been reported of which 3 died. Serial serum calcium determinations should be made in such infants and they should be observed closely for signs and symptoms of hypercalcemia.

Fluorimetric determination of calcium in serum with calcein blue.

Calcium was determined in serum by fluorimetry with calcein blue (CB) in a strongly alkaline solution (0.1 M KOH). Triethanolamine and N-(2-hydroxyethyl)iminodiacetic acid were used to mask iron, copper, zinc and magnesium. The relative standard deviation of the slope of a typical working curve was 0.45%. This value corresponds to confidence limits of 3.53 ± 0.02 at the 95% level. The correlation coefficient was 0.9999. The mean value of calcium in a 20-µl sample of Quality Control Serum was within the appropriate limits of the reference sample. The changes in the structure of CB on standing at high pH are discussed.

Fluorimetric determination of calcium in serum with calcein : Complexation of Calcein with Calcium and Alkali Metals

Calcium (0–50 μM) is determined by measuring the fluorescence of its calcein complexes in strongly alkaline solutions. The effects of alkali metal complexation are described, and the nature of the calcium complexes is investigated. The method is applied to serum.

Are the toxicological effects of scorpion envenomation related to tissue venom concentration?

M. Ismail and M. A. Abd-Elsalam. Are the toxicological effects of scorpion envenomation related to tissue venom concentration? Toxicon 26, 233 – 256, 1988. — The pharmacokinetics of 125I-labelled Androctonus amoreuxi venom and its lethal fraction was studied in rabbits. Comparative pharmacokinetic studies of labelled A. amoreuxi, Leisurus quinquestriatus and Buthotus judaicus venoms were carried out in guinea-pigs. The pharmacokinetics of A. amoreuxi venom was also studied in rats. Groups of rats were injected with labelled A. amoreuxi venom and killed at frequent time intervals for the determination of the relative tissue venom concentration as a function of time. Several groups of rabbits were injected with A. amoreuxi venom and serial blood samples withdrawn at time intervals comparable with those used in the pharmacokinetic studies for the determination of serum glucose, insulin, cortisol, total proteins, albumin, globulins, cholesterol, total bilirubin, urea, uric acid, bicarbonate, alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, sodium, potassium, calcium and phosphorus. The packed cell volume, and total and differential leucocyte counts were also determined. In another series of experiments continuous monitoring of the electrocardiograms of rabbits following venom injection was made to correlate any abnormalities with tissue venom concentration. All three venoms and the lethal fraction showed an open two-compartment behaviour with rapid distribution half-lives ranging between 4 and 7 min and overall elimination half-lives of 4.2 to 13.4 hr. The behaviour of A. amoreuxi venom was not markedly different in the three species of animals used. In a given species (guinea-pigs) the behaviour of the three venoms was not markedly different. Correlation of the ECG changes with cardiac venom concentration showed that arrhythmias and infarction occurred at times when cardiac concentration was very low, indicating that the cardiac abnormalities might result from indirect factors. Comparison of the course of the biochemical changes with venom concentration in the central compartment indicated that the site of action of the venom is not located in the central compartment. Correlation of the intensity of the biochemical effects with venom concentration in the peripheral compartment revealed an apparent delay in the onset and peak of action. This was explained by assuming that the tissue compartment could be divided into a rapidly accessible and a slowly accessible compartment with the venom acting through the slowly accessible compartment. There was also the possibility of the venom acting indirectly through the release of other substances or transformation to an intermediate. It is concluded that since the venom acts indirectly through the release of autopharmacologic substances, treatment with specific blockers might be more effective than with antivenom which has a very slow distribution rate.

Micro-Injection System for Flame Atomic Absorption Spectrometry Using Carrier Solution

A new micro-infection system for flame atomic absorption spectrometry has been devised. In this system, a small amount of sample, 20 to 100 μl, is injected in the stream of a carrier solution through a sample inlet and then fed into a nebulizer. Use of the carrier solution is found to be effective to minimize a sample volume and to reduce physical and chemical interferences. The carrier solution of water reduces the physical interference caused by the increased viscosity of sample solution which contained 5% albumin, and the carrier solution of 2000 ppm lanthanum suppresses the chemical interference caused by aluminum and phosphoric acid in the determination of magnesium and calcium. This method has been successfully applied to the determination of magnesium, calcium, copper and zinc in serum. The analytical results agreed well with those obtained by conventional flame atomic absorption, the relative standard deviation (RSD) being less than 5,1%