Hypoparathyroidism laboratory findings: Difference between revisions

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__NOTOC__
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{{Hypoparathyroidism}}
{{Hypoparathyroidism}}
{{CMG}}; {{AE}} {{DAMI}}
{{CMG}}; {{AE}} {{Anmol}}


==Overview==
==Overview==
An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].
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.
 
OR
 
Laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].
 
OR
 
[Test] is usually normal among patients with [disease name].
 
OR
 
Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].
 
OR
 
There are no diagnostic laboratory findings associated with [disease name].


==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 (25[OH] vitamin D) levels. [[PTH]] degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice.
*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.
If necessary, measuring [[Cyclic adenosine monophosphate|cAMP]] ([[cyclic AMP]]) in the urine after an intravenous dose of [[PTH]] can help in the distinction between [[hypoparathyroidism]] and other causes.
*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]]:
<div style="text-align: center;">'''Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin)''' </div>
:*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]]
**[[Hypocalcemia|Low serum calcium level]]
**Normal to [[Hyperphosphatemia|elevated serum phosphate]] concentration<br>
<br>
{|
! style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Disorder}}
! rowspan="2" style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Hypoparathyroidism}}
! rowspan="2" style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Classic vitamin D deficiency}}
! rowspan="2" style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Pseudohypoparathyroidism}}
! rowspan="2" style="background: #4479BA; text-align: center;" |{{fontcolor|#FFF|Hypomagnesemia}}
|-
! style="background: #7d7d7d; text-align: center;" |{{fontcolor|#FFF|Laboratory findings}}
|-
| style="background: #DCDCDC; text-align: center;" |Serum calcium concentration
| style="background: #F5F5F5; text-align: center;" | ↓
| style="background: #F5F5F5; text-align: center;" | ↓
| style="background: #F5F5F5; text-align: center;" | ↓
| style="background: #F5F5F5; text-align: center;" | Slightly ↓
|-
| style="background: #DCDCDC; text-align: center;" |Intact PTH
| style="background: #F5F5F5; text-align: center;" | ↓
| style="background: #F5F5F5; text-align: center;" | ↑
| style="background: #F5F5F5; text-align: center;" | ↑
| style="background: #F5F5F5; text-align: center;" | Inappropriately ↓
|-
| style="background: #DCDCDC; text-align: center;" |Serum phosphate concentration
| style="background: #F5F5F5; text-align: center;" | ↑
| style="background: #F5F5F5; text-align: center;" | ↓/Low-normal
| style="background: #F5F5F5; text-align: center;" | ↑
| style="background: #F5F5F5; text-align: center;" | --
|}
<br>


===Calculation of corrected total calcium===
==Biochemical Tests==
===Serum Calcium===
*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.
*[[Serum albumin]] should be measured and if found low, corrected [[calcium]] should be measured.


<div style="text-align: center;">Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin) </div style>
===Serum Parathyroid Hormone===
*Method of choice for measuring intact [[parathyroid hormone]] include Immunoradiometric assay (IMRA) or Immunochemiluminescent assay (ICMA).<ref name="pmid1993319">{{cite journal |vauthors=Endres DB, Villanueva R, Sharp CF, Singer FR |title=Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: performance in the differential diagnosis of hypercalcemia and hypoparathyroidism |journal=Clin. Chem. |volume=37 |issue=2 |pages=162–8 |year=1991 |pmid=1993319 |doi= |url=http://clinchem.aaccjnls.org/content/clinchem/37/2/162.full.pdf}}</ref>


In this formula, serum calcium is measured in mg/dL and serum albumin is measured in gm/dL.
===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.


*Normal or inappropriately low intact parathyroid hormone level with subnormal serum albumin corrected total or ionized calcium values in a patient is diagnostic of hypoparathyroidism. Hypomagnesemia should be rule out before.
===Serum 25-Hydroxy Vitamin D===
*Serum 25-hydroxy [[vitamin D]] should be measured to rule out [[vitamin D deficiency]] as a cause of [[hypocalcemia]].


==Laboratory Findings==
===Serum Albumin===
*[[Serum albumin]] should be measured as [[Hypoalbuminemia|low albumin]] will give falsely low total serum [[calcium]].


*There are no diagnostic laboratory findings associated with [disease name].
===24-Hour Urinary Calcium===
OR
*24-Hour [[urinary]] [[calcium]] [[excretion]] is indicated by the [[urinary]] calcium:creatinine clearance ratio.
*An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].
*Hypoparathyroidism and [[vitamin D deficiency]] have low [[Urinary system|urinary]] [[calcium]] [[excretion]].
*[Test] is usually normal among patients with [disease name].
*[[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>
*Laboratory findings consistent with the diagnosis of hypoparathyroidism include:
**Low parathyroid hormone
**Low serum calcium level
**Normal to elevated serum phosphate concentration


*Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].
===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==
==References==
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[[Category:Disease]]
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[[Category:Endocrinology]]
[[Category:Parathyroid disorders]]
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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

Corrected total calcium = measured total calcium + 0.8 (4.0 − serum albumin)


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 25-Hydroxy Vitamin D

Serum Albumin

24-Hour Urinary Calcium

24-Hour Urinary Magnesium

References

  1. ↑ Shoback D (2008). "Clinical practice. Hypoparathyroidism". N. Engl. J. Med. 359 (4): 391–403. doi:10.1056/NEJMcp0803050. PMID 18650515.
  2. ↑ 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.
  3. ↑ 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.
  4. ↑ 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.

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