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RC Peds Endo 2023 > Ca, Phos, Bone > Flashcards

Ca, Phos, Bone Flashcards

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1
Q

Causes low ALP

A
  • HPP
    • Congetnital hypophosphatasia
    • Nutritional deficiencies
    • Zine Def
    • Vit C Def
    • Wilson disease
    • Hypothyroidism
    • Celiac Disease
    • Glucocorticoids
    • Bisphosphonates
    • Pernicious anemia
    • Active caloric restriction
    • Multiple myeloma, other cancers
      • Major trauma or surgery
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2
Q

Cause high ALP

A
  • Bone disease
  • GI disease
    ○ biliary tract obstruction - elevated LFTs too
    ○ liver disease (eg, tumor, abscess, granulomas, or amyloidosis) - isolated elevated ALP
  • Transient hyperphosphatasemia of infancy and early childhood (benign)
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3
Q

FGF23 receptor
- what kind of R
- what does it do
- what does it cause

A
  • tyrosine kinase recetpro
  • degradation of NaPi cotransporter
  • lowers [phos]
  • also decreases calcitriol
  • increases 24-OHase
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4
Q

SnS HypoCa

A

irritability
jitteriness
tremors
perioral and acral paresthesia
poor feeding
laryngospasm
muscle cramp
lethargy
seizure

Trousseau’s sign
Chvostek’s sign

prolonged QTc
arrhythmia
bradycardia

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5
Q

Neonatal HypoCa DDx

A
  • Early-Onset (0-72 hours)
    ○ IDM, IUGR, birth asphyxia, prematurity
    ○ Maternal hypercalcemia
    ○ Hypoparathyroidism (transient or permanent)
  • Late-Onset (>72 hours)
    ○ High phosphorus intake - in formula
    § Because this steals all the Ca to complex w so decreases [Ca]
    ○ Low magnesium
    Maternal vitamin D deficiency – Hypoparathyroidism
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6
Q

HyperCa SnS

A

Polyuria, polydipsia
Anorexia, nausea and vomiting
Failure to thrive in infants and toddlers
Constipation
Hypotonia
Irritability/seizure/depression
Renal calculi
Bone pain
Hypertension

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7
Q

how does SCFN cause hyper Ca

A

Granulomatous disease (1-alpha hydroxylase - high levels of 1,25 OH Vit D from macrophages)

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8
Q

how does Williams syndrome cause hyperCa

A

Incr absorption of Ca and dcr clearance

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9
Q

features to distinguish FHH from other causes of hyper Ca

A

Low calcium in urine (hypocalciuria)
Family history of the same (autosomal dominant)
Lower PTH
No findings on ultrasound or imaging (ie: no adenomas)
Hypercalcemia is present from a young age
Elevated Mg (or upper limit of normal)
Typically mild hypercalcemia
Typically asymptomatic

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10
Q

Mgmt HyperCa

A

Acute
– Hydration (normal saline) - (1.5-2xmaintenance)
– Loop diuretics– for fluid overload (not first line) – do not recommend prolonged use
– Oral phosphate for binding of calcium in intestine
– Calcitonin
– Dialysis
– Bisphosphonate

Long term
- bisphosphonates
*denosumab
– Glucocorticoids (inhibits 1 ⍺ hydroxylase activity + decreases GI absorption of Ca)
– Calcimimetic agents (Allosteric activators of CaSR-> reduce PTH secretion)
– Parathyroidectomy
– cinacalcet for neonates/inoperable cases -> Stimulates the CaSR

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11
Q

Hungry bone syndrome

A

After prolonged hyperparathyroid - acute removal of PTH so bones take back up the Ca

– Severe hypocalcemia
– Hypophosphatemia
– Hypomagnesemia
– Elevated alkaline phosphatase

  • Due to chronic increase in bone resorption
  • Bone influx of minerals after acute drop in PTH levels

Hungry bones – rapid aggressive remineralization after prolonged exposure to PTH

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12
Q

sx hypophos

A

Muscle weakness
Fatigue
Acute neurological symptoms – paresthesia, altered mental status, seizures

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13
Q

causes hypophos

A

**Renal phosphate wasting (main cause)
**Acute phosphate redistribution
○ Refeeding syndrome
**High PTH
○ PTH inhibits phosphate reabsorption in proximal renal tubule

**Decreased GI uptake / intestinal absorption
○ Starvation, e.g. AN
○ Vitamin D deficiency
○ Malabsorption
○ Inhibition of phosphate absorption (eg, antacids containing aluminum or magnesium, niacin)
○ Chronic alcoholism
○ Steatorrhea and chronic diarrhea
○ Vitamin D deficiency or resistance (VDDR1: mutation in 1-alpha-hydroxylase)

**Renal losses / increased urinary excretion
○ Hyperparathyroidism – primary and secondary
○ Hypophosphatemic rickets (X-linked and AD)
○ Vit D Def or resistance
○ RTA (fanconi)
○ Diuretic therapy
○ Hypomagnesemia
○ Aldosteronism
○ HHRH : Hereditary hypophosphatemic rickets with hypercalciuria (LOF mutations in Na-Pi IIc)
○ Oncogenic osteomalacia
**Intracellular shifts / internal redistribution
○ Alkalosis (metab or resp)
○ Increased insulin secretion (particularly refeeding)
○ Hungry bone syndrome
○ Administration of corticosteroids, epi, lactate, glucose, insulin
○ Recovery from hypothermia

**Misc
* Acute gout
* Hypokalemia
* Carcinoma – tumor induced osteomalacia
* DKA
* Alcohol withdrawal

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14
Q

what is Fanconi syndrome

A

Renal proximal tubular disorder leading to loss of:
- phos
- gluc
- K
- bicarb
- UA
- AA
- proximal RTA

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15
Q

HypoMg
- what does it do to PTH
- sx

A

Chronic hypoMg -> Decreases PTH secretion and action
==”Stuns the gland”
Acutely hypoMg -> parathyroid increases secretion of PTH

Symptoms of hypocalcemia
* Irritability
* Muscle twitches
* Jitteriness
* Tremors
* Poor feeding
* Lethargy
* Seizures

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16
Q

what does hyperMg do

A

suppresses PTH
Stimulates CaSR

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17
Q

Genetic syndromes assoc w hyperparathyroid

A

MEN 1
MEN 2a
Hyperparathyroidism - jaw tumor syndrome
MEN 4
Familial isolated hyperparathyroidism
Neonatal severe primary hyperpathyroidism
Nonsense PHPT

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18
Q

clinical features of rickets

A

○ Craniotabes
○ Frontal bossing
○ Delayed closure of fontanelles
○ Delayed eruption of teeth with poor enamel formation, pitting
○ Rachitic rosary
○ Harrison’s groove
○ Pectus carinatum
○ Scoliosis and kyphosis
○ Flaring of the metaphyses of the long bones
○ Bowing of legs
○ Poor growth, short stature
○ Muscle hypotonia -> pronounced potbelly and waddling gait
○ Pathologic fracture

adolescents:
○ Bone pain (usually lower spine, pelvis, lower extremities) and muscle weakness
○ Bone tenderness
○ Fracture (rib, vertebrae, long bone)
○ Difficulty walking and waddling gait
Muscle spasms, cramps, a positive Chvostek’s sign, tingling/numbness, and inability to ambulate

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19
Q

Xray of rickets

A
  • Widening of growth plate (metaphysis)
  • Irregularity of the epiphyseal-metaphyseal junctions
  • Metaphyseal cupping, splaying and fraying (vs. sharp demarcation and slightly convexshape)
    -Osteopenia
    -Bowing of long bones (if wt bearing)
    -Pseudofractures (= Looser’s zones or Milkman’s fractures)
    -unhealed microfractures at points of stress or at entry point of blood vessels into bone
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20
Q

Rickets or osteopenia of prematurity

A

causes”
– Prematurity (Failure to accrue bone mineral in third trimester)
– Chronic medical problems; Medications used to treat them
– Inadequate intake of minerals post birth, TPN dependency, aluminum toxicity
= lack of dietary Ca, phos, Vit D + lack of Vit D can cause decreased absorption of Ca and Phos

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21
Q

RF for MBD of prem

A
  • <28 wga
  • <1500g
  • TPN for >4weeks
  • CLD
  • long term diuretic use
  • NEC grade 2 or more
  • fluid restriction (TFI <150)
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22
Q

what do you see on xray in scruvy

A

osteopenic with thin cortices
sclerotic bands

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23
Q

Primary causes of osteoporosis

A

1) OI
2) Idiopathic juvenile osteoperosis

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24
Q

Types of OI

A

○ Mild - type 1
○ Type 2 - lethal
○ Type 3 - severe
○ Type 4 - moderate
○ Type 5 - moderate

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25
Secondary causes of osteoporosis
1) Malignancy - leukemia - solid tumours 2) Inflammatory disorders - Rheuatoid arthritis -IBD -CF -Celiac disease 3) Muscle weakness or reduced mobility -DMD -CP -Developmental delay -Autism 4) Osteotoxic drugs -Glucocorticoids -Methotrexate -GnRH agonists 5) Endocrinopathies -Hypogonadism -Hyperthyroidism -Cushing
26
Meds causing osteoporosis
○ Glucocorticoids ○ Anticonvulsants ○ Methotrexate ○ Antiepileptics ○ Heparin ○ Immunosuppressants: MTX, Cyclosporine A ○ Lithium ○ Antiretrovirals ○ GnRH agonist ○ Sex hormone deprivation with gonadotropin releasing hormone agonists or medroxyprogesterone acetate. ○ Thyrotoxicosis ○ Diuretics L-thyroxine suppressive therapy (only post menopausal women)
27
how do GC cause osteoporosis
CELLS - increased apoptosis osteoblasts and chondrocytes - decreased proliferation osteocytes - inhibition of osteoblastogenesis - prolongs osteoclast life - enhanced osteoclastogenesis HORMONES/OTHER FACTORS - decreased OPG - increased FGF23 - decreased expression type 1 collagen - decreased WNT signalling ENZYMES - impaired 1aOHase Ca coming into body - increased Ca excretion in the kidney - decreased Ca absoriotn in gut OTHER HORMONES - impaired androgens - decreased sex hormones - decreased GH and IGF1
28
OI findings
○ Craniofacial: -Triangular facies -Wormian bones (extra skull bones between normal sutures) -Macrocephaly -Chiari malformation -Hydrocephalus -Hearing loss ○ Optho: -Blue sclerae ○ Dental: -Dentinogenesis imperfecta (teeth discolored and translucent) ○ Respiratory: -Pulmonary hypoplasia -Respiratory failure ○ MSK: -Hypermobility -Fragility fractures -Long bone deformities (can have bowing) -Short stature -Scoliosis -osteoporosis - long bone fractures
29
problems w the bone
low bone mass low bone quality abnormal bone geometry bone deformation
30
how do bisphosphates work
- bind to hydroxyapatite - stop osteoclasts from binding - cause osteoclast apoptosis
31
peds uses of bisphosphanates
○ Hypecalcemia ○ Primary Osteoporosis § OI § OJI ○ Secondary Osteoporosis except eating disorders – --Fibrous Dysplasia --Immobilization -- DMD -- CP -- juvenile arthritis ○ Fibrous dysplasia - juvenile Paget's (idiopathic hyperphosphatasia)
32
S/E bisphos
* Acute ○ Fever ○ Myalgia ○ Abdominal pain, dyspepsia ○ Vomiting ○ Hypocalcemia, hypophosphatemia ○ Bone pain ○ Pain at infusion site ○ Headache ○ Allergic reaction ○ *Acute phase reaction usually only after 1st dose * Chronic ○ Inflammatory disorders of the eye ○ Osteonecrosis of the jaw (in the elderly) ○ Induced osteopetrosis ○ atypical femur fracture
33
denosumab - what is it - when to use - big issue
- monoclonal ab to RANK-L - Giant cell tumour - osteoporosis - Aneurysmal bone cysts rebound hyperCa NOT IN OI anymore
34
osteopetrosis
- Malignant infantile osteopetrosis - AD form - Xlinked defect in bone resorption increased BMD bone fragility narrow bone marrow space - pancytopenia compression of CN hypoCa - sz Infantile: Definitive treatment for most of the genetic lesions is hematopoietic stem cell transplantation.
35
what is seen in PHP w bone
fibrous dysplasia Soft tissue calcification
36
PTH-R activating mutation
Jansen’s Metaphyseal Chondrodysplasia - short-limbed dwarfism and characteristic skeletal abnormalities activating mutations in the PTH/PTHrP receptor that result in ligand-independent cAMP accumulation Hypercalcemia and hypophosphatemia low or undetectable serum levels of PTH and PTHrP.
37
what meds affect renal Ca excretion
corticosteroids: increase Ca excretion furosemide: increase Ca excretion thiazide diuretics decrease Ca excretion
38
what happens when PTH acts on the PTH-R
PTH-R expresses: more RANK-L less OPG This leads to more osteoclast action and more bone turnover
39
hyper Ca DDx
Bone resorption: - hyperPTH -- primary, MEN, familial isolated - thyrotoxicosis - vit D intoxication - hypervitaminosis A - immobilization High Ca intake - High Ca intakes for phosphate binding in renal failure - milk alkali syndrome - vitamin D intoxication Other: - subcutaneous fat necrosis - malignancy (osteolytic mets, PTHrP) - Williams syndrome - Familial hypocaliuric hypercalcemia - Meds: thiazides, lithium, theophylline - Adrenal insufficiency - pheochromocytoma - hypophosphatasia - rhabdomyolysis - distal RTA - Excess PTHrP (ie. tumour induced) - hyperthyroidism
40
HyperCa in Neonates - DDx
1. Excessive intake of calcium or Vit D’ - Exogenous - Milk-alkali - Granulomatous diseases – ectopic production of calcitriol 2. Phosphate depletion 3. SC fat necrosis, Granulomatous disease (1-alpha hydroxylase) 4. Williams syndrome 5. Endocrinopathies: - primary adrenal insufficiency - severe hypothyroidism, or hyperthyroidism 6. Malignancy - lytic bone lesions or PTHrP 7. Meds: - thiazides, lithium, Vit A ,Ca, alkali etc. 8. Genetics 9. Other: 1. Immobilization 2. Persistent PTHrP Maternal hypoparathyroidism Maternal pseudohypoparathyroidism
41
Genetic causes of HyperCa in neonates
1. CYP24A1 2. Jansen metaphyseal chondroplasia (activating mutation of PTH-R) 3. LCT: Congenital lactase and other disaccharide deficiencies (2/2 increased intestinal absorption of Ca promoted by the disaccharides) 4. Infantile hypophosphatasia (TNSALP: mutation in AlkPhos) 5. Mucolipidosis type II 6. Blue diaper syndrome a. defect in absorption of tryptophan, ass/w hypercalcemia and nephrocalcinosis, pathogenesis unclear 7. Antenatal Bartter syndrome type 1 (SLC12A1) and type 2 (KCNJ1) 8. Distal RTA
42
Familial Hypocalciuric Hypercalcemia - gene - labs
Due to dominantly inherited INACTIVATING mutation in the CaSR Benign elevation in Ca PTH normal to slightly high
43
Chvostek's sign
Percussing the facial nerve approximately 2 cm anterior to the ear, causes contraction of the ipsilateral facial muscles.
44
Trousseau's sign
Inflate the BP cuff to approximately 20–30 mmHg above systolic for 3 minutes. Characterized by carpal spasms, with adduction of the thumb, flexion of the metacarpophalangeal joint, extension of the interphalangeal joints, and flexion of the wrist
45
neonatal hypoCa
maternal diabetes maternal hyperparathyroidism Vitamin D deficiency High intake of alkali or magnesium sulfate Use of anticonvulsants prematurity/LBW birth trauma/asphyxia sepsis, toxemia hypoparathyroidism (DiGeorge) hypomagnesemia Acute/chronic renal failure excessive phos intake inadequate calcium intake vitamin D deficiency hyperphosphatemia pseudohypoparathyroidism Vitamin D def or resistance Osteopetrosis type II
46
where is the GNAS gene imprinted
paternal allele imprinted in the kidney (ie silenced)
47
what is the AHO phenotype
short stature round facies obesity brachydactyly developmental delay dental hypoplasia basal ganglia calcifications decreased bone density subcutaneous calcifications lenticular opacities strabismus cognitive impairment
48
inherited defects in CaSR
Inactivating – High PTH & high calcium 1. Neonatal severe hyperparathyroidism (AR) 2. Familial Benign Hypocalciuric hypercalcemia(AD) Activating – Low PTH & low calcium 1. AD Hypocalcemic hypercalciuria
49
acquired defects in CaSR
Autoimmune hypocalciuric hypercalcemia (hyperparathyroidism) - Blocking Ab vs. CaSR - Acts like inactivating mutation Autoimmune acquired hypoparathyroidism - Stimulating Ab vs. CaSR - Acts like activating mutation
50
type of R - VDR
nuclear steroid hormone receptor
51
definition of rickets
1) Deficient mineralization at the growth plate + 2) architectural disruption of this structure.
52
signs of low phosphate
Muscle weakness/dysfunction/fatigue Neuro sx if acute hypophos (parathesias, altered mental status, seizure)
53
meds that can cause osteoporosis
Glucocorticoids GnRH agonist Anticonvulsants Heparin Immunosuppressants: MTX, Cyclosporine A Lithium Antiretrovirals Diuretics L-thyroxine suppressive therapy
54
differentiating features between FHH and primary hyperparathyroidism
i) No findings on ultrasound ii) Lower PTH iii) Higher urinary calcium excretion iv) AD family history v) Hypercalcemia is present from young age (from birth if investigations are done) vi) Elevated magnesium
55
What medication can modulate CaSR? How does it work?
i) Magnesium: binds to CaSR and causes reduced PTH secretion and lower calcium ii) Cinacalcet: Can upregulate CaSR expression
56
osteogenesis imperfecta - what protein is implicated - features of the protein that are important for normal function
type 1 collagen most commonly caused by mutations in genes encoding the alpha-1 and alpha-2 chains of type I collagen or proteins involved in posttranslational modification of type I collagen i. Has to form helix ii. Helices have to form triple helix
57
RF for hungry bone syndrome
high ALP, parathyroid adenoma >5 cm, very elevated calcium and PTH the osteitis fibrosa cystica
58
what are the bone lesions in hyperparathyroidism?
Osteitis fibrosa cystica are the bone lesions seen in the phalanges and skull in hyperparathyroidism
59
how long can nodules appear in SCFN
6 weeksw
60
what is craniosyostosis seen in
X-linked hypophosphatemic rickets
61
what are causes of bone resorpton
- hyperPTH -- primary, MEN, familial isolated - thyrotoxicosis - vit D intoxication - hypervitaminosis A - immobilization
62
preferred site for DEXA in children
lumbar spine and total body
63
acute hypoCa - what to watch for
laryngospasm
64
what is Blomstrand chondroplasia
(PTHR1–loss of function mutation) PTH resistance
65
5 factors for osteoporosis in DMD
1) reduced muscle tension on bone 2) steroids 3) delayed puberty 4) chronic inflammation (attempted repair of damaged muscle fibres) 5) immobility
66
maternal factors risk of MBD
Vitamin D deficiency Placental insufficiency (impacts mineral transfer) Pre-eclampsia Chorioamnitis Alcohol intake Smoking
67
neonatal factors factors risk of MBD
Vitamin D deficiency Prematurity 2 wks) Inadequate calcium supplementation Inadequate phosphate supplementation Necrotizing enterocolitis Chronic glucocorticoids Chronic diuretics Chronic lung disease Malabsorptionw
68
when does the majority of Ca and phosphate accretion occur
third trimester of pregnancy resulting in bone and growth plate mineralization
69
4 inherited causes of PTH dependent hypercalcemia
MEN1 - hyperparathyroidism Autosomal dominant, MEN1 tumor suppressor gene (menin protein) MEN2a - hyperparathyroidism Autosomal dominant, RET (634 most common) Familial hypocalciuric hypercalcemia Autosomal dominant, inactivating mutation in CASR Neonatal severe hyperparathyroidism Autosomal recessive, inactivating mutation in CASR

RC Peds Endo 2023 (17 decks)

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