Hypoparathyroidism laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
Diagnosis of hypoparathyroidism is made by measurement of serum [[calcium]] (total and ionized), [[serum albumin]] (for correction), [[phosphate]], intact [[parathyroid hormone]] (PTH), and [[25-hydroxy vitamin D]] levels.Normal or inappropriately low serum intact [[parathyroid hormone]] (PTH) concentration in patients with subnormal [[serum albumin]] corrected total or ionized [[calcium]] concentration diagnostic of hypoparathyroidism. | Diagnosis of hypoparathyroidism is made by measurement of [[serum]] [[calcium]] (total and ionized), [[serum albumin]] (for correction), [[phosphate]], intact [[parathyroid hormone]] ([[PTH]]), and [[25-hydroxy vitamin D]] levels. Normal or inappropriately low serum intact [[parathyroid hormone]] ([[PTH]]) concentration in patients with subnormal [[serum albumin]] corrected total or ionized [[calcium]] concentration diagnostic of hypoparathyroidism. | ||
==Laboratory Findings== | ==Laboratory Findings== | ||
*Diagnosis of hypoparathyroidism is made by measurement of serum [[calcium]] (total and ionized), [[serum albumin]] (for correction), [[phosphate]], intact [[parathyroid hormone]] (PTH), and [[25-hydroxyvitamin D]] levels.<ref name="pmid18650515">{{cite journal |vauthors=Shoback D |title=Clinical practice. Hypoparathyroidism |journal=N. Engl. J. Med. |volume=359 |issue=4 |pages=391–403 |year=2008 |pmid=18650515 |doi=10.1056/NEJMcp0803050 |url=}}</ref> | *Diagnosis of hypoparathyroidism is made by measurement of [[serum]] [[calcium]] (total and ionized), [[serum albumin]] (for correction), [[phosphate]], intact [[parathyroid hormone]] ([[PTH]]), and [[25-hydroxyvitamin D]] levels.<ref name="pmid18650515">{{cite journal |vauthors=Shoback D |title=Clinical practice. Hypoparathyroidism |journal=N. Engl. J. Med. |volume=359 |issue=4 |pages=391–403 |year=2008 |pmid=18650515 |doi=10.1056/NEJMcp0803050 |url=}}</ref> | ||
*[[PTH]] degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice. | *[[PTH]] degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice. | ||
*Normal or inappropriately low serum intact [[parathyroid hormone]] (PTH) concentration in patients with subnormal [[serum albumin]] corrected total or ionized [[calcium]] concentration diagnostic of hypoparathyroidism. | *Normal or inappropriately low serum intact [[parathyroid hormone]] ([[PTH]]) concentration in patients with subnormal [[serum albumin]] corrected total or ionized [[calcium]] concentration diagnostic of hypoparathyroidism. | ||
*[[Hypomagnesemia]] and [[vitamin D deficiency]] should be ruled out as cause of hypocalcemia before making a diagnosis of hypoparathyroidism. | *[[Hypomagnesemia]] and [[vitamin D deficiency]] should be ruled out as cause of [[hypocalcemia]] before making a diagnosis of hypoparathyroidism. | ||
*Calculation of corrected total [[calcium]]: | *Calculation of corrected total [[calcium]]: | ||
<div style="text-align: center;">'''Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin)''' </div> | <div style="text-align: center;">'''Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin)''' </div> | ||
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**[[Hypocalcemia|Low serum calcium level]] | **[[Hypocalcemia|Low serum calcium level]] | ||
**Normal to [[Hyperphosphatemia|elevated serum phosphate]] concentration<br> | **Normal to [[Hyperphosphatemia|elevated serum phosphate]] concentration<br> | ||
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! style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Disorder}} | ! style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Disorder}} | ||
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==Biochemical Tests== | ==Biochemical Tests== | ||
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*Measurement of total serum [[calcium]] with automatic techniques has similar or even more reliability than serum ionized [[calcium]] measurement.<ref name="pmid8964825">{{cite journal |vauthors=Silverberg SJ, Bilezikian JP |title=Evaluation and management of primary hyperparathyroidism |journal=J. Clin. Endocrinol. Metab. |volume=81 |issue=6 |pages=2036–40 |year=1996 |pmid=8964825 |doi=10.1210/jcem.81.6.8964825 |url=https://watermark.silverchair.com/api/watermark?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAfQwggHwBgkqhkiG9w0BBwagggHhMIIB3QIBADCCAdYGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMs2QB8t_zFXzSZJ4bAgEQgIIBp8fw3_iunlmFW1rMhoY9MDPeg_lHu7iYzuIrfwXHubghqdXOMvdWyttCOOgR3PHFZtE5IkmNB4hRahVQsPzHGwh5kiBmLGp9W8OQwFxrCIH0sBqjOxOiYc_yGAs0ybxF1mEh929-YxivBBC43EW1yFtSmwplSQfAWah7w6yxXbUhV8umq3pGQxqYDClp47IR7TyVeEneWZz85Z7MS80V4c-yZPG1ZPxQR-1kPk3rdji_8bAeXwJKRGScWzKPqSEQvXFWLV4sHwqgTrU53HSkURUJb8u-w4EOHMjtUATJPoGgFsZOcrf_xtPBZmcI_v5G3RO_cJDHueDwQNfRaGIO2ztcToFGmVpER4vGhqfrtr7mXHPNPyUUOa-_KWPE-qxDrUCG8kevm0tM8MButJkAmVdBxrIC4mSd8sAZb3KcfSKt9RUXFJpIiDoOut21ZFEGEU8O7vwjw4RhxridsegEUiCFWCxHftX9qUqELn90AJ2Fg1olxH9jI46KnEJPd7MNYReTvdeX5erBZmXjmP5oCT6vLYUbRLjXxyJQRl-d5N9O0vfTgZ5bbA}}</ref> | *Measurement of total serum [[calcium]] with automatic techniques has similar or even more reliability than serum ionized [[calcium]] measurement.<ref name="pmid8964825">{{cite journal |vauthors=Silverberg SJ, Bilezikian JP |title=Evaluation and management of primary hyperparathyroidism |journal=J. Clin. Endocrinol. Metab. |volume=81 |issue=6 |pages=2036–40 |year=1996 |pmid=8964825 |doi=10.1210/jcem.81.6.8964825 |url=https://watermark.silverchair.com/api/watermark?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAfQwggHwBgkqhkiG9w0BBwagggHhMIIB3QIBADCCAdYGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMs2QB8t_zFXzSZJ4bAgEQgIIBp8fw3_iunlmFW1rMhoY9MDPeg_lHu7iYzuIrfwXHubghqdXOMvdWyttCOOgR3PHFZtE5IkmNB4hRahVQsPzHGwh5kiBmLGp9W8OQwFxrCIH0sBqjOxOiYc_yGAs0ybxF1mEh929-YxivBBC43EW1yFtSmwplSQfAWah7w6yxXbUhV8umq3pGQxqYDClp47IR7TyVeEneWZz85Z7MS80V4c-yZPG1ZPxQR-1kPk3rdji_8bAeXwJKRGScWzKPqSEQvXFWLV4sHwqgTrU53HSkURUJb8u-w4EOHMjtUATJPoGgFsZOcrf_xtPBZmcI_v5G3RO_cJDHueDwQNfRaGIO2ztcToFGmVpER4vGhqfrtr7mXHPNPyUUOa-_KWPE-qxDrUCG8kevm0tM8MButJkAmVdBxrIC4mSd8sAZb3KcfSKt9RUXFJpIiDoOut21ZFEGEU8O7vwjw4RhxridsegEUiCFWCxHftX9qUqELn90AJ2Fg1olxH9jI46KnEJPd7MNYReTvdeX5erBZmXjmP5oCT6vLYUbRLjXxyJQRl-d5N9O0vfTgZ5bbA}}</ref> | ||
*An [[hypocalcemia|low serum calcium]] should be confirmed by repeat measurement. | *An [[hypocalcemia|low serum calcium]] should be confirmed by repeat measurement. | ||
*[[Serum albumin]] should be measured and if found low, corrected calcium should be measured. | *[[Serum albumin]] should be measured and if found low, corrected [[calcium]] should be measured. | ||
===Serum Parathyroid Hormone=== | ===Serum Parathyroid Hormone=== | ||
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===Serum Magnesium=== | ===Serum Magnesium=== | ||
*Serum [[magnesium]] concentration should be measured to rule out [[hypomagnesemia]] (or sometimes [[hypermagnesemia]]) as a cause of hypocalcemia. | *Serum [[magnesium]] concentration should be measured to rule out [[hypomagnesemia]] (or sometimes [[hypermagnesemia]]) as a cause of [[hypocalcemia]]. | ||
*[[Hypomagnesemia]] as a contributor to [[hypocalcemia]] may be difficult to rule out as serum [[magnesium]] levels may be normal even if there depletion of [[intracellular]] [[magnesium]] stores. | *[[Hypomagnesemia]] as a contributor to [[hypocalcemia]] may be difficult to rule out as serum [[magnesium]] levels may be normal even if there depletion of [[intracellular]] [[magnesium]] stores. | ||
*Serum [[magnesium]] decreases to subnormal levels as [[magnesium]] depletion progresses. | *Serum [[magnesium]] decreases to subnormal levels as [[magnesium]] depletion progresses. | ||
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===Serum Albumin=== | ===Serum Albumin=== | ||
*[[Serum albumin]] should be measured as [[Hypoalbuminemia|low albumin]] will give falsely low total serum [[calcium]]. | |||
===24-Hour Urinary Calcium=== | ===24-Hour Urinary Calcium=== | ||
*24-Hour [[urinary]] [[calcium]] [[excretion]] is indicated by the [[urinary]] calcium:creatinine clearance ratio. | *24-Hour [[urinary]] [[calcium]] [[excretion]] is indicated by the [[urinary]] calcium:creatinine clearance ratio. | ||
*Hypoparathyroidism and [[vitamin D deficiency]] have low [[Urinary system|urinary]] [[calcium]] [[excretion]]. | *Hypoparathyroidism and [[vitamin D deficiency]] have low [[Urinary system|urinary]] [[calcium]] [[excretion]]. | ||
*[[Hypocalcemia|Hypocalcemic]] patients with activating mutations in the extracellular [[calcium-sensing receptor]] have a substantially higher [[Urinary system|urinary]] calcium:creatinine clearance ratio.<ref name="pmid11134112">{{cite journal |vauthors=Yamamoto M, Akatsu T, Nagase T, Ogata E |title=Comparison of hypocalcemic hypercalciuria between patients with idiopathic hypoparathyroidism and those with gain-of-function mutations in the calcium-sensing receptor: is it possible to differentiate the two disorders? |journal=J. Clin. Endocrinol. Metab. |volume=85 |issue=12 |pages=4583–91 |year=2000 |pmid=11134112 |doi=10.1210/jcem.85.12.7035 |url=}}</ref> | *[[Hypocalcemia|Hypocalcemic]] patients with activating mutations in the [[extracellular]] [[calcium-sensing receptor]] have a substantially higher [[Urinary system|urinary]] calcium:creatinine clearance ratio.<ref name="pmid11134112">{{cite journal |vauthors=Yamamoto M, Akatsu T, Nagase T, Ogata E |title=Comparison of hypocalcemic hypercalciuria between patients with idiopathic hypoparathyroidism and those with gain-of-function mutations in the calcium-sensing receptor: is it possible to differentiate the two disorders? |journal=J. Clin. Endocrinol. Metab. |volume=85 |issue=12 |pages=4583–91 |year=2000 |pmid=11134112 |doi=10.1210/jcem.85.12.7035 |url=}}</ref> | ||
===24-Hour Urinary Magnesium=== | ===24-Hour Urinary Magnesium=== | ||
*24-hour [[urinary]] [[magnesium]] level measurement before initiation of treatment for [[hypocalcemia]] is useful if [[magnesium deficiency]] is detected as a cause of [[hypocalcemia]]. | *24-hour [[urinary]] [[magnesium]] level measurement before initiation of treatment for [[hypocalcemia]] is useful if [[magnesium deficiency]] is detected as a cause of [[hypocalcemia]]. | ||
*Elevated or even detectable [[urinary]] levels of [[magnesium]] suggest [[magnesium]] depletion due to renal losses since [[kidney]] should conserve [[magnesium]] in depleted body stores. | *Elevated or even detectable [[urinary]] levels of [[magnesium]] suggest [[magnesium]] depletion due to [[renal]] losses since [[kidney]] should conserve [[magnesium]] in depleted body stores. | ||
==References== | ==References== | ||
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{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} | ||
[[Category:Disease]] | |||
[[Category:Medicine]] | |||
[[Category:Endocrinology]] | |||
[[Category:Parathyroid disorders]] | |||
[[Category:Up-To-Date]] | |||
Latest revision as of 22:18, 29 July 2020
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anmol Pitliya, M.B.B.S. M.D.[2]
Overview
Diagnosis of hypoparathyroidism is made by measurement of serum calcium (total and ionized), serum albumin (for correction), phosphate, intact parathyroid hormone (PTH), and 25-hydroxy vitamin D levels. Normal or inappropriately low serum intact parathyroid hormone (PTH) concentration in patients with subnormal serum albumin corrected total or ionized calcium concentration diagnostic of hypoparathyroidism.
Laboratory Findings
- Diagnosis of hypoparathyroidism is made by measurement of serum calcium (total and ionized), serum albumin (for correction), phosphate, intact parathyroid hormone (PTH), and 25-hydroxyvitamin D levels.[1]
- PTH degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice.
- Normal or inappropriately low serum intact parathyroid hormone (PTH) concentration in patients with subnormal serum albumin corrected total or ionized calcium concentration diagnostic of hypoparathyroidism.
- Hypomagnesemia and vitamin D deficiency should be ruled out as cause of hypocalcemia before making a diagnosis of hypoparathyroidism.
- Calculation of corrected total calcium:
Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin)
- In this formula, serum calcium is measured in mg/dL and serum albumin is measured in gm/dL.
- Laboratory findings consistent with the diagnosis of hypoparathyroidism include:
- Low parathyroid hormone
- Low serum calcium level
- Normal to elevated serum phosphate concentration
| Disorder | Hypoparathyroidism | Classic vitamin D deficiency | Pseudohypoparathyroidism | Hypomagnesemia |
|---|---|---|---|---|
| Laboratory findings | ||||
| Serum calcium concentration | ↓ | ↓ | ↓ | Slightly ↓ |
| Intact PTH | ↓ | ↑ | ↑ | Inappropriately ↓ |
| Serum phosphate concentration | ↑ | ↓/Low-normal | ↑ | -- |
Biochemical Tests
Serum Calcium
- Measurement of total serum calcium with automatic techniques has similar or even more reliability than serum ionized calcium measurement.[2]
- An low serum calcium should be confirmed by repeat measurement.
- Serum albumin should be measured and if found low, corrected calcium should be measured.
Serum Parathyroid Hormone
- Method of choice for measuring intact parathyroid hormone include Immunoradiometric assay (IMRA) or Immunochemiluminescent assay (ICMA).[3]
Serum Magnesium
- Serum magnesium concentration should be measured to rule out hypomagnesemia (or sometimes hypermagnesemia) as a cause of hypocalcemia.
- Hypomagnesemia as a contributor to hypocalcemia may be difficult to rule out as serum magnesium levels may be normal even if there depletion of intracellular magnesium stores.
- Serum magnesium decreases to subnormal levels as magnesium depletion progresses.
Serum 25-Hydroxy Vitamin D
- Serum 25-hydroxy vitamin D should be measured to rule out vitamin D deficiency as a cause of hypocalcemia.
Serum Albumin
- Serum albumin should be measured as low albumin will give falsely low total serum calcium.
24-Hour Urinary Calcium
- 24-Hour urinary calcium excretion is indicated by the urinary calcium:creatinine clearance ratio.
- Hypoparathyroidism and vitamin D deficiency have low urinary calcium excretion.
- Hypocalcemic patients with activating mutations in the extracellular calcium-sensing receptor have a substantially higher urinary calcium:creatinine clearance ratio.[4]
24-Hour Urinary Magnesium
- 24-hour urinary magnesium level measurement before initiation of treatment for hypocalcemia is useful if magnesium deficiency is detected as a cause of hypocalcemia.
- Elevated or even detectable urinary levels of magnesium suggest magnesium depletion due to renal losses since kidney should conserve magnesium in depleted body stores.
References
- ↑ Shoback D (2008). "Clinical practice. Hypoparathyroidism". N. Engl. J. Med. 359 (4): 391–403. doi:10.1056/NEJMcp0803050. PMID 18650515.
- ↑ Silverberg SJ, Bilezikian JP (1996). "Evaluation and management of primary hyperparathyroidism". J. Clin. Endocrinol. Metab. 81 (6): 2036–40. doi:10.1210/jcem.81.6.8964825. PMID 8964825.
- ↑ Endres DB, Villanueva R, Sharp CF, Singer FR (1991). "Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: performance in the differential diagnosis of hypercalcemia and hypoparathyroidism" (PDF). Clin. Chem. 37 (2): 162–8. PMID 1993319.
- ↑ Yamamoto M, Akatsu T, Nagase T, Ogata E (2000). "Comparison of hypocalcemic hypercalciuria between patients with idiopathic hypoparathyroidism and those with gain-of-function mutations in the calcium-sensing receptor: is it possible to differentiate the two disorders?". J. Clin. Endocrinol. Metab. 85 (12): 4583–91. doi:10.1210/jcem.85.12.7035. PMID 11134112.