Lab: Metabolic & Endocrine Pathology

Question 1

What is the normal serum calcium level range?

Answer 1

8.6-10.6 mg/dl

Question 2

What is the normal serum phosphate level range?

Answer 2

1.5-4.5 mg/dl

Question 3

What does DEXA measure?

Answer 3

Bone density

Question 4

What is the DEXA T-score for osteopenia?

Answer 4

-1.0 to -2.5

Question 5

What is the DEXA T-score for osteoporosis?

Answer 5

Below -2.5

Question 6

In short, what is rickets?

Answer 6

Impaired bone mineralization

Question 7

What are the expected lab findings for rickets?

Calcium:
Phosphate:
PTH:
Alkaline phosphatase:

Answer 7

Calcium: decreased
Phosphate: decreased
PTH: increased
Alkaline phosphatase: increased

Question 8

Osteomalacia is an adult ___ deficiency

Answer 8

Vitamin D

Question 9

What is the typical cause of hypervitaminosis D?

Answer 9

Over supplementation

Question 10

What are the lab findings for Vitamin D toxicity (hypervitaminosis D)?

Calcium:
PTH:

Answer 10

Calcium: increased (in blood and urine)
PTH: decreased

Question 11

A patient has a serum calcium level of 7.4 mg/dl.
Would PTH production be elevated or decreased?
What term describes this serum calcium value?

Answer 11

PTH would be elevated (hyperparathyroidism) due to hypocalcemia

Question 12

Which Vitamin D metabolite is necessary to facilitate calcium absorption in the gut?

Answer 12

Calbindin

Question 13

Which Vitamin D metabolite interacts with PTH on bone to increase serum calcium levels?

Answer 13

Calcitriol

Question 14

Calcitriol, a Vitamin D metabolite, works with ___ to ___ serum calcium levels

Answer 14

works with PTH to increase serum calcium levels

Question 15

In response to increased PTH levels, what functions does the kidney perform to increase serum calcium levels?

Answer 15

• Increase calcitriol
• Conserve calcium
• Excrete phosphate

Question 16

What hormonal secretion helps decrease serum calcium levels by sequestering calcium in the mitochondria of the cells?

Answer 16

Calcitonin (from parathyroid)

Question 17

What clinical term describes the blood results of a patient with a phosphate value of 10.3 mg/dl?

Answer 17

Hyperphosphatemia

Question 18

This bone was sectioned with a butter knife
What metabolic pathology is present?

Answer 18

Osteomalacia

Question 19

What do the white areas in this bone indicate?

Answer 19

Increased osteoid (organic, unmineralized tissue)

osteomalacia

Question 20

There is reduction in normal ___ bone in this specimen

Answer 20

trabecular

osteomalacia

Question 21

How does the organic vs inorganic bone composition of this femur compare with a normal adult specimen?

Answer 21

Increased organic to inorganic ratio

osteomalacia

Question 22

stress strain

How does the replacement of trabecular bone with osteoid alter the biomechanical properties of bone?

Answer 22

Bones soften and weaken making them more likely to bend and break

osteomalacia

Question 23

This is the proximal metaphysis and diaphysis of the humerus
What is the dense white substance that has accumulated in the marrow cavity at the purple arrow?

Answer 23

Osteoid

osteomalacia

Question 24

This is the proximal metaphysis and diaphysis of the humerus
Would the bending of this specimen’s diaphysis generally be reversible without surgical intervention?

Answer 24

No

osteomalacia

Question 25

Which metabolic pathology created these changes in bone?

Answer 25

Rickets

Question 26

At what age did these changes occur?

Answer 26

Young age | rickets

Question 27

Where does calcitriol come from? How does it affect plasma calcium and PTH?

Answer 27

Calcitriol comes form the kidney Calcium increases, PTH decreases

Question 28

What is the function of calbindin?

Answer 28

Binds calcium in the gut, increases calcium absorption

Question 29

What are the expected lab results for this patient? Calcium: Phosphate:

Answer 29

Calcium: decreased Phosphate: decreased | rickets

Question 30

How would serum levels of phosphate and calcium contribute to this bowing?

Answer 30

Less calcium and phosphate means the bone is more organic, thus more elastic and more plastic, leading to deformity | rickets

Question 31

What is the presentation of this knee?

Answer 31

Normal skeletally immature knee

Question 32

What is unusual about the metaphyses seen here?

Answer 32

Paintbrush metaphyses; widened | rickets

Question 33

What sort of fracture has occurred in the right fibula?

Answer 33

Oblique diaphyseal and transverse distal diaphyseal fractures: complete, noncomminuted, insufficiency (stress) pathological fractures | rickets

Question 34

How are these joints affected by their pathology?

Answer 34

Not dislocated, but subluxated/misaligned | rickets

Question 35

How has the composition of this individual's bones changed in response to stress?

Answer 35

More bone laid down according to weight bearing (Wolff's law) | rickets

Question 36

Based on this radiograph, what is your suspected diagnosis?

Answer 36

Rickets

Question 37

What disease pathogenesis (cellular events) would explain the bones in this radiograph?

Answer 37

Decreased cartilage formation, decreased osteoid mineralization, and increased organic to inorganic ratio leads to soft and weak bones increasing risk of fracture | rickets

Question 38

What are the expected lab results for this patient? ESR: Vitamin D: Calcium: PTH: Phosphate:

Answer 38

ESR: elevated (inflammation associated) Vitamin D: deficient Calcium: decreased (needs vitamin D) PTH: increased (trying to increase calcium resorption in kidneys) Phosphate: decreased (PTH decreases phosphate resorption)

Question 39

What are the potential etiologies of this condition?

Answer 39

* Indadequate dietary intake of Vitamin D or sun (acquired) * Vitamin D dependent rickets type I: defective hydroxylation of metabolites in liver or kidney (inherited) * Vitamin D dependent rickets type II: end organ insensitivity to vitamin D (inherited) | rickets

Question 40

What treatment would you recommend for a patient with an acquired deficiency and a radiograph similar to this?

Answer 40

Vitamin D supplementation

Question 41

A 1 year-old female presents with bleeding gums and bilateral swelling in the thighs. The patient’s guardian reports constant crying, and her temperature is recorded at 98.6 F (37 C). The child also shows bruises in multiple stages of healing. The parents report no traumatic incidents to explain the bruises. Blood work and radiographs are ordered. What are the relevant signs and symptoms in this case?

Answer 41

Bleeding gums and easy bruising (vessel fragility) | scurvy

Question 42

A 1 year-old female presents with bleeding gums and bilateral swelling in the thighs. The patient’s guardian reports constant crying, and her temperature is recorded at 98.6 F (37 C). The child also shows bruises in multiple stages of healing. The parents report no traumatic incidents to explain the bruises. Blood work and radiographs are ordered. What category of pathology (infection, fracture, collagen synthesis, etc.) matches the intial signs and symptoms we see for this patient?

Answer 42

Collagen synthesis and metabolic | scurvy

Question 43

Is the radiopaque outline around the cortex in the radiograph osteolytic or osteoblastic activity? What could create the outline around the cortex?

Answer 43

Osteoblastic activity created by subperiosteal bleeding/hemorrhage | scurvy

Question 44

A 1 year-old female presents with bleeding gums and bilateral swelling in the thighs. The patient’s guardian reports constant crying, and her temperature is recorded at 98.6 F (37 C). The child also shows bruises in multiple stages of healing. The parents report no traumatic incidents to explain the bruises. Blood work and radiographs are ordered. What diagnosis best fits this case?

Answer 44

Scurvy (hypovitaminosis C) | metabolic

Question 45

The formation of which tissue type affecting bone is altered during this pathology? How?

Answer 45

Collagen synthesis; vitamin C is important for hydroxylation of prolyl and lysyl residues in collagen (hydroxyproline and hydroxylysine) | scurvy

Question 46

What is causing the discoloration indicated by the blue arrows? Is this obervation potentially reversible?

Answer 46

Repeated/chronic hemorrhage Irreversible | scurvy

Question 47

What does DEXA measure?

Answer 47

Bone density

Question 48

What is the meaning of a DEXA T-score?

Answer 48

Comparison of bone density to that of a healthy young adult

Question 49

What is the meaning of a DEXA Z-score?

Answer 49

Comparison of bone density to that of other patients the same age

Question 50

What are the following DEXA scores according to World Health Organization? Normal: Osteopenia: Osteoporosis:

Answer 50

Normal: +1 to -1 Osteopenia: -1 to -2.5 Osteoporosis: -2.5 or lower

Question 51

A 53 year-old female patient of yours has asthma and has been using steroids to control her condition for decades. She was also prescribed a blood thinner following a recent heart attack and the placement of a stent in the right carotid artery. Based on her age and medications, her primary care provider suggested she receive a DEXA scan. On her next visit, she brings the results to show you. What risk factors does this patient have that could impact bone density?

Answer 51

* Age * Steroids * Blood thinners * Association with cardiovascular history

Question 52

When does peak bone mass occur?

Answer 52

Ages 25-30

Question 53

What are some factors that may negatively impact peak bone mass?

Answer 53

* Physical activity (lack thereof) * Diseases * Fractures * Medications * Hormones

Question 54

What would you recommend for an osteopenic/osteoporotic patient?

Answer 54

* Weight bearing and strength training exercise * Calcium and vitamin D supplementation * Alterations to chiropractic treatment plan

Question 55

Your 53 year-old patient (with osteoporosis) fell and caught herself on an outstretched hand. She presented to the emergency room with pain in the left wrist. How would you describe this racture?

Answer 55

Osteoporotic/pathologic fracture; Colles fracture

Question 56

What is the term for a common distal radius fracture, often acquired after falling on an outstretched hand?

Answer 56

Colles fracture

Question 57

Which is more common in cases of rickets, genu varum or genu valgum?

Answer 57

Genu varum (bowlegged)

Question 58

A 2 year-old child presents with hypotonia (decreased muscle tone) and delayed growth. The child is unable to stand and there is bowing in the legs (genu varum) and arms bilaterally. You also note that the patient presents with frontal bossing, rachitic rosary, and pectus carinatum. The patient’s blood work reveals serum calcium levels at the low end of normal. Blood work also indicated that the patient is hypophosphatemic but has high serum levels of Vitamin D. What is the likely diagnosis for this patient?

Answer 58

Rickets ## Footnote Vitamin D being stored trying to increase calcium

Question 59

Besides genu varum, what are some other bony presentations found in children with rickets?

Answer 59

* Pectus carinatum (Pigeon breast) * Frontal bossing * Rachitic rosary

Question 60

This enlargment of the costochondral joints of the ribs is seen in which pathology?

Answer 60

Rickets

Question 61

In which pathology do we see pectus carinatum in children?

Answer 61

Rickets

Question 62

In which pathology do we see pediatric frontal bossing that grows via intramembranous ossification?

Answer 62

Rickets

Question 63

What produces genu varum in cases of rickets?

Answer 63

Lack of control over endplate growth

Question 64

What are the expected PTH levels in the case of rickets?

Answer 64

Increased

Question 65

A patient's presentation indicates rickets, but their blood work revealed high Vitamin D levels in the blood What could explain this?

Answer 65

Body is trying to retain/store vitamin D because of hypocalcemia