Laboratory Tests in the Diagnosis of Hyperparathyroidism in Hypercalcemic Patients

Strott, Charles A.

doi:10.7326/0003-4819-68-1-188

Cited by 69 publications

(18 citation statements)

References 78 publications

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“…While some investigators have attributed a normal total calcium level in patients with normocalcemic hyperparathyroidism to an increased ratio of ionized and ultrafiltrable calcium to total calcium in these patients compared to normal subjects, others did not confirm it (15,26,27). Resistance to the effect of PTH in increasing renal tubular reabsorption of calcium resulting in higher urinary calcium has also been postulated (28).…”

Section: Discussionmentioning

confidence: 99%

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

Gomes

Lage

Lazaretti-Castro

et al. 2004

Braz J Med Biol Res

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The response to an oral calcium load test was assessed in 17 hypercalciuric nephrolithiasis patients who presented elevated parathyroid hormone (PTH) irrespective of the ionized calcium (sCa 2+ ) levels. Blood samples were collected at baseline (0 min) and at 60 and 180 min after 1 g calcium load for serum PTH, total calcium, sCa 2+ , and 1.25(OH) 2 D 3 determinations. According to the sCa 2+ level at baseline, patients were classified as normocalcemic (N = 9) or hypercalcemic (N = 8). Six healthy subjects were also evaluated as controls. Bone mineral density was reduced in 14/17 patients. In the normocalcemic group, mean PTH levels at 0, 60 and 180 min (95 ± 76, 56 ± 40, 57 ± 45 pg/ml, respectively) did not differ from the hypercalcemic group (130 ± 75, 68 ± 35, 80 ± 33 pg/ml) but were significantly higher compared to healthy subjects despite a similar elevation in sCa 2+ after 60 and 180 min vs baseline in all 3 groups. Mean total calcium and 1.25(OH) 2 D 3 were similar in the 3 groups. Additionally, we observed that 5 of 9 normocalcemic patients presented a significantly higher concentration-time curve for serum PTH (AUC 0',60',180' ) than the other 4 patients and the healthy subjects, suggesting a primary parathyroid dysfunction. These data suggest that the individual response to an oral calcium load test may be a valuable dynamic tool to disclose a subtle primary hyperparathyroidism in patients with high PTH and fluctuating sCa 2+ levels, avoiding repeated measurements of both parameters.

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Section: Discussionmentioning

confidence: 99%

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

Gomes

Lage

Lazaretti-Castro

et al. 2004

Braz J Med Biol Res

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“…The use of such a factor is also of value in comparing Urinary calcium themselves little help in the differentiation of the hypercalcaemia of primary hyperparathyroidism from that due to other causes. Hypercalciuria occurs in 20-30% of patients with primary hyperparathyroidism (Pyrah, Hodgkinson, and Anderson, 1966;Strott and Nugent, 1968) and since urinary calcium excretion represents the end result of the processes of filtration and tubular reabsorption of diffusible plasma calcium, any patient with hypercalcaemia will have an increased filtered calcium load which will be reflected as an increased urinary calcium excretion.…”

Section: Plasma Calciummentioning

confidence: 99%

“…The changes measured following calcium infusions are usually based on alterations in urinary phosphorus excretion as an index of parathyroid suppression (Pronove and Bartter, 1961). The value of these tests in the differential diagnosis of hypercalcaemia has however, been questioned since hyperparathyroid responses have been observed in other hypercalcaemics and negative results have been obtained in patients with proven primary hyperparathyroidism (Strott and Nugent, 1968).…”

Section: Calcium Tolerance Testmentioning

confidence: 99%

Laboratory Tests in the Differentiation of Hyperparathyroidism from other Causes of Hypercalcaemia

Wills

1970

Ann Clin Biochem

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“…Despite this, use of the diet persisted because it was generally heId to enhance the diagnostic value of urine calcium rneasurement. However, in about one-third of patients with primary hyperparathyroidism, the urinary calcium on a low calcium diet is normal (McGeown, 1965) and the test is of no diagnostic value (Strott & Nugent, 1968). Nevertheless, there remain several reasons for studying urinary calcium in primary hyperparathyroidism.…”

Section: Introductionmentioning

confidence: 98%

Effect of Cellulose Phosphate and Dietary Calcium Restriction in Primary Hyperparathyroidism

Parfitt

1975

Clinical Science

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1. The bivalent cation-binding agent, cellulose phosphate, together with a low calcium diet was given for 6 days to nine patients with primary hyperparathyroidism subsequently verified at surgery. 2. Urinary calcium fell promptly by 8-4 mmol/24 h, and by 70% and reached amounts below 4-0 mmol/24 h in five of the nine patients. The magnitude of fall may have been related to increased synthesis of vitamin D by the skin in a sub-tropical environment. Plasma magnesium fell steadily and urinary magnesium fell by 80%. 3. The plasma calcium showed two types of response. In five patients there was no significant change because a reduction in calcium load was offset by a further increase in the already high tubular reabsorption of calcium. In the remaining four patients, the tubular reabsorption of calcium was at a higher level initially and failed to increase further on the experimental regime, with a corresponding fall in plasma calcium. 4. The hypercalcaemia of primary hyperparathyroidism can be explained by increased renal tubular reabsorption of calcium; net bone resorption makes only a small contribution but an additional factor dependent on the blood-bone equilibrium is not ruled out. 5. Comparison with other published data suggests that the fall in urinary calcium in response to a calcium-depleting regimen is prevented by concurrent depletion of inorganic phosphate and may be enhanced by concurrent depletion of magnesium. 6. Persistence of hypercalcaemia combined with an increase in tubular reabsorption of calcium in response to cellulose phosphate may be of diagnostic value in suspected primary hyperparathyroidism. 7. Cellulose phosphate may be of value in stone prevention in patients with primary hyperparathyroidism who are unsuitable for surgical treatment.

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Laboratory Tests in the Diagnosis of Hyperparathyroidism in Hypercalcemic Patients

Cited by 69 publications

References 78 publications

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

Laboratory Tests in the Differentiation of Hyperparathyroidism from other Causes of Hypercalcaemia

Effect of Cellulose Phosphate and Dietary Calcium Restriction in Primary Hyperparathyroidism

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