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Clin path test 4 > Calcium, Phophorus, & Magnesium > Flashcards

Calcium, Phophorus, & Magnesium Flashcards

1
Q

Parathyroid gland

A
  • Main endocrine organ controlling Ca/P metabolism
  • Live on the thyroid gland
  • Chief cells
    • if low Ca PTH made
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2
Q

PTH

A
  • Mobilizes Ca and P from bone
  • Makes kidneys save Ca
  • Makes kidneys make most active form of vitamin D
    • Vitamin D makes GI absorb Ca and P
  • net effect PTH => kidneys pee out Phosphorus (inc Ca dec P)
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3
Q

Vitamin D

A
  • made in kidney
    • stimulated by PTH
  • Actions
    • Inc GI absorption of Ca and P***
    • Inc bone resorption
    • Inc renal resorption
  • inc Ca and P in the blood
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4
Q

Calcitonin

A
  • PTH antagonist
  • Produced by C cells of thyroid gland
  • Stimulated by high Ca+
  • Inhibits reabsorption of Ca and P from bone and kidney
  • dec Ca and dec P
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5
Q

Serum Calcium

Total Ca

Free (ionized Ca)

A
  • 40% bound to albumin
  • 50% ionized (active and regulated)
  • 10% complexed
  • Total Calcium
    • provided with serum biochem profile
  • Free (ionized) Calcium
    • can be measured with certain machines
    • portion that is hormonally regulated and contributes to pathologic states
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6
Q

Ca Concentration depends on

A
  • 1) dietary intake
  • 2) intestinal absorption (duodenum)
    • inc by calcitrol (active vit D3)
    • dec by malabsorption, maldigestion, cortisol
  • 3) skeletal resportion
    • modified by: PTH, Calcitonin, Age, Osteolytic dz
  • 4) renal reabsorption and excretion
    • modified by: PTH in distal tubules
    • Ca removed based on GRF in proximal tubules and loop of Henle
  • 5) other losses
    • saliva, lactation, fecal, sweat (horses)
  • 6) Regulatory hormone concentrations
    • PTH, Calcitriol, Calcitonin, PTHrP, others
  • 7) Acid base status
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7
Q

pH effects

Acidosis:

Alkalosis

A
  • Acidosis => inc ionized Calcium (free Ca)
  • Alkalosis => dec ionized Ca

* in acidosis, Hydrogen ions take up space on albumin and more Ca is in blood

*in alkalosis, fewer Hydrogen ions are on albumin and more Ca is bound, and less free Ca in blood

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8
Q

Analytes for Ca status

A
  • Total calcium: standard analyzer
  • Free (ionized) Ca: ion specific electrode
  • Inorganic phosphorus: standard analyzer
  • Parathyroid hormone (PTH): immunoassay
  • Parathyroid hormone related peptide (PTHrp): immunoassay
  • Vitamin D
  • send Ca panel to Michigan state
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9
Q

Hypocalcemia: Hypoalbuminemia

A
  • 40% Ca bound to albumin
    • dec albumin = dec total Ca
  • free (ionized) Ca stays the same
  • benign
  • Most common cause of dec in total Ca
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10
Q

Free (Ionized Ca conc)

A
  • Inferred from
    • total Ca conc
    • Albumin conc
    • Acid base status
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11
Q

Hypocalcemia

A
  • Inapparent with mild dec Ca
  • inc neuron excitability (low Ca = easier signal conduction)
    • nervous, trembling, panting, m. fasciculation, stiff gain, muscle cramping
  • Cats
    • intense facial rubbing, licking paws, tetanic paralysis
  • Cows
    • flaccid paralysis, seizures
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12
Q

Hypocalcemia Causes

A

HARP IS ALE

  • Hypoparathyroidism, Hyperparathyroidism (secondary, nutritional)
  • Albumin (hypoalbuminemia)
  • Renal failure (not horses)
  • Pancreatitis, Phosphorus (hyperphosphatemia)
  • Intestinal malabsorption, intracellular shift
  • Spurious, sepsis
  • Alkalosis
  • Lactation
  • Ethylene Glycol
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13
Q

Hypoparathyroidism

Hyperparathyroidism

A
  • Hypoparathyroidism
    • less PTH production
      • => less Ca released from bone
      • => More Ca lost in urine
    • Less active Vitamin D made
      • => less Ca uptake from GI
  • Nutritional/secondary Hyperparathyroidism
    • Improper diet formulations => hypocalcemia (low Ca or Vit D)
    • Hyperparathyroidsim => secondary in an attempt to correct blood Ca level
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14
Q

Renal Failure and hypocalcemia

A
  • Dec calcitriol (active Vit D3) formation by kidney
    • dec intestinal absorption of Ca
    • PTH less effective at releasing Ca from bone
  • Inc P will dec Ca
  • Ionized Ca is low more often than total Ca
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15
Q

Pancreatitis

Phosphorous (hyperphosphatemia)

A
  • Pancreatitis => we don’t really know
  • hyperphosphatemia
    • phosphate containing enemas
    • mineralization of soft tissue when Total Ca X P > 70
  • Avoid Ca supplementation unless
    • seizure, twitching, tremor, sev hypocalcemia
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16
Q

Intestinal malabsorption

Intracellular shift

A
  • Intestinal malabsorption
    • Dec absorption of Ca ++ and Vit D
    • Concurrent panhypoproteinemia
  • Intracellular shift
    • pancreatitis
    • myopathies: Ca can move intracellulary in necrosis
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17
Q

Spurious

Sepsis

A
  • Spurious
    • contamination of samples with EDTA (chelates Ca to keep blood from clotting)
    • K in tube => pseudohyperkalemia
  • Sepsis
    • Mechanism….?
    • check free (ionized) Ca in critically ill
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18
Q

Lactational Hypocalcemia

A
  • Eclampsia
    • emergency medical condition
    • life-threatening drop in blood Ca in nursing mothers
    • occurs when puppies are 1-5 weeks of age
    • CS
      • Puerperal tetany
        • stiff limbs, inability to stand or walk
      • tremors, weakness, paralysis
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19
Q

Eclampsia

(periparturient hypocalcemia)

A
  • 1-3 weeks post partum
  • Small breed dogs
  • Loss of Ca in milk/skeletal development
  • Seizures, trembling, twitching, shaking, stiffness
  • Treatment: IV Calcium gluconate
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20
Q

Periparturient hypocalcemia

  • 4 year old Hostein cow, flaccid paralysis
A
  • Dystocia, uterine torsion diagnosed at dairy
  • Ionized-Ca2+ 0.6 1.1-1.3 mm/L (range)
  • Excess Ca loss due to fetal skeletal development and loss in milk
  • Inadequate absorption from intestine/release from bone
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21
Q

Ethylene Glycol

A
  • metabolites of this toxin bind Ca++
  • Can result in hypocalcemia and Ca++ Oxalate Crystalluria
  • Intoxication with oxalate containing plants can also cause hypocalcemia
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22
Q

Significance of hypercalcemia

A
  • Approximately 5% are young growing animals
  • Approximately 60% are transient (not worked up)
  • Approximately 15% persistent and pathological
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23
Q

Hypercalcemia

CS

A
  • PU/PD-Inhibits ADH, dysregulation of aquaporins
  • Lethargy, weakness, constipation
  • Mineralization of soft tissue - when Calcium X Phosphorus > 70
  • Calcium containing uroliths
24
Q

Hypercalcemia Causes

GOSHDARNIT

A
  • G: Granulomatous
  • O: Osteolysis
  • S: Spurious
  • H: Primary Hyperparathyroidism
  • D: Vitamin D Toxicosis
  • A: Addison’s Disease, Age
  • R: Renal Disease
  • N: Neoplasia
  • I: Idiopathic
  • T: Hypothermia
25
Hypervitaminosis D Cause
* Vitamin D toxicity * Over supplementation with dietary source * Exposure to owner medications * Rodenticides with Cholecalciferol (vit D precurs.) * Plants containing vitamin D glycosides * Cestrum diurnum, Solanum malacoxylon * Granulomatous disease * Activation of Vitamin D by macrophages
26
Hypervitaminosis D Mechanisms
* Vitamin D inc Ca resorption of bone * Vitamin D inc Ca & Phosphorus absorption from intestine * **Hypercalcemia & hyperphosphatemia** * These patients at greater risk for soft tissue mineralization
27
Spurious hypercalcemia
* Lipemia, sample handling * hemolysis * mostly young dogs
28
Hypercalcemia Primary Hyperparathyroidism
* Hormones secreted by * functional adenoma (more common) * Hyperplastic gland * Functional carcinoma * Do more advanced panel * PTH
29
Hypoadrenocorticism/Addison's
* Common cause of hypercalcemia in dogs * Total Ca inc +/- ionized Ca * May be inc reabsorption of Ca * Responds to corticosteroid tx and/or volume replacement
30
Hypercalcemia Renal Failure
* **horse thing** renal failure * commonly associated with inc Ca * dietary * inc intestinal absorption * do not activate Vit D in kidney * Ionized Ca normal to low \*important for distinguishing from hyperparathyroidism with secondary renal failure
31
Chronic renal failure
* Hypercalcemia is common in horses * **iCa usually normal to low** * PTH often elevated * In dogs, inc total Ca due to inc complexed Ca (ionized and protein-bound normal) (24% vs 11% complexed protein) phosphates, citrates, lactates, bicarbonates, oxalates \*Important when distinguishing from hyperparathyroidism with secondary renal failure
32
Humoral hypercalcemia of malignancy
* Humoral hypercalcemia of malignancy * Most common cause of hypercalcemia * Lymphoma * Apocrine gland adenocarcinoma of anal sac * Multiple myeloma * **PTH-related protein** * similar in structure and funtion to PTH * can be produced by tumors * measure in dogs and cats * other compounds secreted by tumors such as Vit D like steroid and osteoclast activating factor
33
4 year old MC Golden Retriever Humoral hypercalcemia of malignancy
* Apocrine gland adenocarcinoma: anal gland * Ionized Calcium: 1.8 mmol/L (normal 1.25-1.45) * Intact PTH: 0.00 pmol/L (normal 3.00-17.00) * PTHrp: 5.9 pmol/L (normal 0.0-1.0)
34
Idiopathic hypercalcemia
cat thing rule out other causes not for other species
35
Further diagnostics for hypercalcemia
* Ionized calcium * CBC, Serum chem profile, UA * Thorough physical exam * palpate anal area, lymph nodes * radiography/ultrasound (Parathyroid glands) * Measure PTHrP * Measure PTH * Measure Vit D
36
Phosphorus
* Mineralization of bone * 85% of P in bones and teeth * Critical for high-energy phophoryl units of metabolic intermediates * Remaining 15% is in high energy bonds (ATP), DNA, Phospholipids, intracellular acid base buffering * Structural phosphoproteins and phospholipids * Inorganic phosphate anions play a role in acid base metabolism
37
Phosphorus regulation PTH Calcitonin Vit D Growth Hormone
* PTH: **decreases P** * decreases tubular reabsorption * Calcitonin: **decreases P** * inhibits bone resoprtion * inc movement into tissues * dec renal tubular resporption * Vitamin D: **increases P** * **​**stimulates absorption from intestine and kidney * inhibits PTH synthesis * Growth Hormone: **Increases P** * **​increases renal tubular resorption**
38
Chem stats common in young, growing animals from bone growth
* inc P * inc Ca * inc ALP
39
Abnormal P conc
* Clinical signs usually due to underlying dz * Assoc with disorders of Ca homeostasis * i.e. intestinal malabsorption * Phosphorus concentrated intracellularly * **Shifts between ICF and ECF** * **​Insulin promotes P entry into cells** * **Bicarb shift P into cells**
40
Insulin and Phosphorus
* Promotes P entry into the cells * for phosphorylation of glucose * decreases serum P
41
Bicarb and Phosphorous
* Bicarb shifts P into cells * alkalemia stimulates PFK enzyme activity in glycolysis * promotes P movement into RBCs * b/c of increased phosphorylation during accelerated glycolysis * decreases serum P
42
Hyperphosphatemia
* Can induce bone resorption * high phosphorus chelates Ca * lowers ionized Ca * Activates PTH secretion * Inc bone resorption * Demineralizes bone * Fibrous osteodystrophy results * Can cause soft tissue mineraliztion * if also hypercalcemic * when Ca X P \> 70
43
Hypercalcemia may result in mineralization of kidneys =\>
* could lead to dec GFR * subsequent normal or inc serum P conc instead of decreased
44
Hyperphosphatemia - causes
* **Decreased renal excretion - #1 cause (Dec GFR)** * Azotemia * pre * renal * post * Herbivores may compensate via intestine * cows and horses in renal failure can have normal to low P * ruptured bladder/urethral obstruction * Disorders of Ca homeostasis * Vit D intox * Primary hypoparathyroidism * Growing animals (bone remodeling) * Shift from intracellular to extracellular fluid * Tissue trauma, rhabdomyolysis * Acute tumor lysis syndrome: chemo in animals with high tumor burden * Iatrogenic * diet, fluids, enemas
45
Hypophosphatemia-causes
* **Anorexia, decreased intestinal absorption** * Disorders of Ca homeostasis * primary hyperparathyroidism * hypercalcemia of malignancy * Vitamin D deficiency * Shift from extracellular to intracellular fluid * with insulin (refeeding syndrom, diabetes treatment) * Alkalosis * Equine renal failure * hypercalcemia * hypophophatemia * Parturient paresis (milk fever) * Lactation * Iatrogenic * phosphate binding antacid
46
Hyposphasphatemia CS
* \< 1.5mg/dL =\> abnormally low ATP levels =\> **intravascular hemolysis** * Neuromuscular signs * Intestinal ileus * Weakness * Ataxia * Seizures
47
11 year old MI Dalmation * Disorientation, ataxia, vomiting for 36 hours * indoor, no known tox exp, currently up to date and healthy * Weakness, fine tremors * Other PE findings WNL
Rule outs! G: granulomatous O: osteolysis S: spurious H: 1 hyperparathyroidism D: Vitamin D toxicosis A: Addison's R: renal N: neoplasia I: Idiopathic T: Hypothermia Primary hyperparathyroidism: removed tumor
48
Alk Phos (ALP)
* Smaller increases more impressive in cats * shorter half-life * Dogs: can be induced by * glucocorticoids * phenobarb
49
Post op hemi parathyroidectomy
* Hypocalcemia * unaffected parathyroid tissue atrophied * PTH short half life: dec Ca2+ 6-8 hours postop * Vitamin D supplemention likely necessary * may need to start tx before sz * goal: maintain low-low normal Ca * stimulation regrowth of atrophied parathyroid tissue * slowly withdraw Vit D over period of months * Hypomagnesemia * chronic hypercalcemia can cause hypoMg * signs sim to dec Ca, distinguished by hypertension * Infection/wound healing
50
Magensium
* Free part and protein bound part * Dietary intake and renal excretion * Imp role in PTH synthesis and release * Facilitates Na/K-ATPase activity in cell membranes * enzyme co-factor for all that use ATP * Structural role in bone formation * Imp in neuromuscular function
51
Hypomagensemia Causes
* Hypoproteinemia * Dec intake (anorexia) * Dec absorption * enteric dz * grass tetany in cattle * inc excretion * diuresis
52
Hypomagnasemia **NAVLE**
* Decreased intake * most common cause in ruminants * **Lush green pasture high in K+ and low in Mg++** * **Grass tetany** * **K+ blocks normal Mg++ absorption in rumen** * **Older calves fed milk-only diets** * **​Milk tetany** * Prolonged anorexia * Poor diet * esp if lactating * Prolonged IV fluid therapy or parenteral nutrition w/out Mg supplementation
53
Cantharidin Toxicity
* Cantharidine from blister beetle * GI and Urinary mucosal irritant * Hypomagnesemia/Hypocalcemia * MOA unknown
54
Manifestations of Hypomagnesemia
* Secondary hypokalemia due to renal wasting of K * hypoMg may lead to reduced Na, K-ATPase function * dec function of Na-K-Cl cotransporter * Mg maintains intracellular K levels * if Mg low, K leaks from cells to ECF and lost from body b/c of decreased reabsorption in kidneys * Impaired PTH production and release leading to secondary hypocalcemia
55
Hypomagnesemia CS
* **Those associated with secondary electrolyte abnormalities** * **​hypokalemia** * **hypocalcemia** * **​Neuromuscular and cardiac abnormalities** * Hyperexcitability * Tremors, fasciculations, ataxia * Frank tetany * Cardiac arrhythmias/possible arrest
56
Female Herefor due to calve in 3 weeks * aggressive * fine tremors * 6 other similar cases recently died * fed mix of alfalfa and grass
Calcium = 9.1 (7-9.8) Phosphorous = 5.2 (4.4-7.5) **Magnesium = 1.1 (1.9-3.5)**
57
Hypermagnesemia
* Dec GFR/dehydration * Clinically less significant * Worry if acute * iatrogenic * **dec GFR** * **​**dehydration * acute renal failure * urethral obstruction * patients can dev * CV probs * Neuro probs * flassid paralysis =\> resp arrest * nausea/vomiting

Clin path test 4 (9 decks)

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