Hypocalcemia laboratory findings: Difference between revisions

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VisualWikitext

Latest revision as of 12:01, 13 August 2018

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vamsikrishna Gunnam M.B.B.S [2]

Overview

Measurement of the serum albumin concentration is essential to distinguish pseudohypocalcemia from true hypocalcemia. Laboratory investigations that detect alterations in parathyroid hormone, vitamin D, and phosphate in the serum or urine aid in the differential diagnosis of the underlying etiologies. Other laboratory tests include serum alkaline phosphatase, liver function tests, coagulation profile, blood urea nitrogen, creatinine, and urinary cAMP levels at baseline or after PTH challenge.

Laboratory Findings

CONFIRM HYPOCALCEMIA

The first step in diagnostic approach to hypocalcemia includes "Repeat" measurement of calcium levels and confirming the levels.
Patient previous levels for serum calcium should also be reviewed, if possible or available.

Hypoalbuminemia

Calcium in blood is bound to albumin and calculation of the serum albumin is essential to distinguish true hypocalcemia.
1 g/dL decrease in the serum albumin levels will lower the total calcium levels by approximately 0.8 mg/dL (0.2 mmol/L).
But these reduction in serum albumin levels does not affect serum ionized calcium levels and therefore no signs of hypocalcemia.
So, a patient who has a serum albumin level that is 2 g/dL (20 g/L) below normal will have a fall in serum total calcium level of 1.6 mg/dL (0.4 mmol/L).

Laboratory findings consistent with the diagnosis of hypocalcemia include

Serum PTH concentrations
Magnesium concentrations
Phosphate concentrations
Vitamin D metabolites

Adjustment for Hypoalbuminemia

Adjustment of total serum calcium concentration for changes in plasma albumin level:^[1]

Adjusted total calcium in mg/dL = Total calcium in mg/dL + 0.8 * (4 - Albumin in g/dL)

Adjusted total calcium in mmol/L = Total calcium in mmol/L + 0.02 * (40 - Albumin in g/L)

Laboratory Differential Diagnosis of Hypocalcemia

Abbreviations: ADHP, autosomal dominant hypoparathyroidism; CKD, chronic kidney disease; Cr, creatinine; Def, deficiency; HP, hyperphosphatemia; HPTH, hypoparathyroidism; PHP, pseudohypoparathyroidism; VDDR, vitamin D-dependent rickets.^[2]

↓Ca

↑PTH

↔↓PTH

↑PO4

↔↓PO4

↔Mg

↓Mg

↑Cr

↔Cr

↓25(OH)D

↔↑25(OH)D

HPTH

ADHP or Mg def

CKD

PHP or HP

Vitamin D def

↓1,25(OH)₂D

↑1,25(OH)₂D

Type I VDDR

Type II VDDR

References

↑ "Correcting the calcium". British Medical Journal. 1 (6061): 598. 1977-03-05. ISSN 0007-1447. PMC 1605322. PMID 843828.CS1 maint: PMC format (link)
↑ Ferri, Fred (2015). Ferri's clinical advisor 2015 : 5 books in 1. Philadelphia, PA: Elsevier/Mosby. ISBN 978-0323083751.

Template:WS Template:WH

[1] "Correcting the calcium". British Medical Journal. 1 (6061): 598. 1977-03-05. ISSN 0007-1447. PMC 1605322. PMID 843828.CS1 maint: PMC format (link)

[2] Ferri, Fred (2015). Ferri's clinical advisor 2015 : 5 books in 1. Philadelphia, PA: Elsevier/Mosby. ISBN 978-0323083751.

[1]

[2]

@@ Line 1: / Line 1: @@
 __NOTOC__
 {{Hypocalcemia}}
-{{CMG}}
+{{CMG}}; {{AE}} {{VKG}}
-Please help WikiDoc by adding more content here.  It's easy!  Click  [[Help:How_to_Edit_a_Page|here]]  to learn about editing.
+==Overview==
+Measurement of the serum [[albumin]] concentration is essential to distinguish pseudohypocalcemia from true hypocalcemia.  Laboratory investigations that detect alterations in [[parathyroid hormone]], [[vitamin D]], and [[phosphate]] in the [[serum]] or urine aid in the differential diagnosis of the underlying etiologies. Other laboratory tests include [[serum]] [[alkaline phosphatase]], [[liver function test]]s, [[coagulation|coagulation profile]], [[blood urea nitrogen]], [[creatinine]], and urinary [[cAMP]] levels at baseline or after PTH challenge.
+==Laboratory Findings==
+==== CONFIRM HYPOCALCEMIA====
+*The first step in diagnostic approach to [[hypocalcemia]] includes '''"Repeat"''' measurement of [[calcium]] levels and confirming the levels.
+*Patient previous levels for [[serum]] calcium should also be reviewed, if possible or available.
+==== Hypoalbuminemia ====
+* [[Calcium]] in [[blood]] is bound to albumin and calculation of the serum albumin is essential to distinguish true hypocalcemia.
+* 1 g/dL decrease in the [[serum albumin]] levels will lower the total [[calcium]] levels by approximately 0.8 mg/dL (0.2 mmol/L).
+* But these reduction in [[serum albumin]] levels does not affect serum ionized calcium levels and therefore no signs of hypocalcemia.
+* So, a patient who has a [[serum albumin]] level that is 2 g/dL (20 g/L) below normal will have a fall in serum total calcium level of 1.6 mg/dL (0.4 mmol/L).
+Laboratory findings consistent with the diagnosis of hypocalcemia include
+* [[Parathyroid hormone|Serum PTH]] concentrations
+* [[Magnesium]] concentrations
+* [[Phosphate]] concentrations
+* Vitamin D metabolites
+==Adjustment for Hypoalbuminemia==
+* Adjustment of total [[Calcium|serum calcium]] concentration for changes in plasma albumin level:<ref>{{Cite journal| issn = 0007-1447| volume = 1| issue = 6061| pages = 598| title = Correcting the calcium| journal = British Medical Journal| date = 1977-03-05| pmid = 843828| pmc = PMC1605322}}</ref>
+: ''Adjusted total calcium in mg/dL = Total calcium in mg/dL + 0.8 * (4 - Albumin in g/dL)''
+: ''Adjusted total calcium in mmol/L = Total calcium in mmol/L + 0.02 * (40 - Albumin in g/L)''
-==Overview==
+==Laboratory Differential Diagnosis of Hypocalcemia==
+<span style="font-size: 85%;">
+'''Abbreviations''':
+ADHP, autosomal dominant hypoparathyroidism;
+CKD, chronic kidney disease;
+Cr, creatinine;
+Def, deficiency;
+HP, hyperphosphatemia;
+HPTH, hypoparathyroidism;
+PHP, pseudohypoparathyroidism;
+VDDR, vitamin D-dependent rickets.<ref>{{cite book | last = Ferri | first = Fred | title = Ferri's clinical advisor 2015 : 5 books in 1 | publisher = Elsevier/Mosby | location = Philadelphia, PA | year = 2015 | isbn = 978-0323083751 }}</ref>
+</span>
-== Laboratory Findings ==
+<div style="font-size: 75%;">
-Suggested initial laboratory studies include the following:
+{{Familytree/start}}
-* Serum calcium
+{{Familytree|boxstyle=border: 0;| | | | | | | | | | | | | | A01 | | | | | | | | | | | | | | | |A01={{F1|↓Ca}}}}
-* Ionized calcium
+{{Familytree|boxstyle=border: 0;| | | | | | | | | |,|-|-|-|-|^|-|-|-|-|-|-|-|-|-|-|-|.| | | | |}}
-* [[Complete blood count]]
+{{Familytree|boxstyle=border: 0;| | | | | | | | | B01 | | | | | | | | | | | | | | | B02 | | | |B01={{F1|↑PTH}}|B02={{F1|↔↓PTH}}}}
-* Blood urea nitrogen (BUN)/creatinine
+{{Familytree|boxstyle=border: 0;| | | | |,|-|-|-|-|^|-|-|-|-|.| | | | | | | | |,|-|-|^|-|-|.| |}}
-* [[Magnesium]]
+{{Familytree|boxstyle=border: 0;| | | | C01 | | | | | | | | C02 | | | | | | | C03 | | | | C04 |C01={{F1|↑PO4}}|C02={{F1|↔↓PO4}}|C03={{F1|↔Mg}}|C04={{F1|↓Mg}}}}
-* [[Albumin]]
+{{Familytree|boxstyle=border: 0;| |,|-|-|^|-|-|.| | | |,|-|-|^|-|-|.| | | | | |!| | | | | |!| |}}
-* [[Phosphorus]]
+{{Familytree|boxstyle=border: 0;| D01 | | | | D02 | | D03 | | | | D04 | | | | D05 | | | | D06 |D01={{F1|↑Cr}}|D02={{F1|↔Cr}}|D03={{F1|↓25(OH)D}}|D04={{F1|↔↑25(OH)D}}|D05={{F2|HPTH}}|D06={{F2|ADHP or Mg def}}}}
-* Amylase/lipase
+{{Familytree|boxstyle=border: 0;| |!| | | | | |!| | | |!| | |,|-|-|^|-|-|.| | | | | | | | | | |}}
+{{Familytree|boxstyle=border: 0;| E01 | | | | E02 | | E03 | E04 | | | | E05 | | | | | | | | | |E01={{F2|CKD}}|E02={{F2|PHP or HP}}|E03={{F2|Vitamin D def}}|E04={{F1|↓1,25(OH)<sub>2</sub>D}}|E05={{F1|↑1,25(OH)<sub>2</sub>D}}}}
+{{Familytree|boxstyle=border: 0;| | | | | | | | | | | | | | |!| | | | | |!| | | | | | | | | | |}}
+{{Familytree|boxstyle=border: 0;| | | | | | | | | | | | | | F01 | | | | F02 | | | | | | | | | |F01={{F2|Type I VDDR}}|F02={{F2|Type II VDDR}}}}
+{{Familytree/end}}
+</div>
 ==References==
 {{Reflist|2}}
-[[Category:Needs content]]
+[[Category:Cardiology]]
+[[Category:Disease]]
+[[Category:Endocrinology]]
+[[Category:Nephrology]]
-Additional laboratory studies to be obtained as part of a more complete evaluation include the following:
+{{WS}}
-* [[Vitamin D]] levels
+{{WH}}
-* [[Parathyroid hormone]]